Set up translation with i18next

i18next-parser.config.js

@@ -0,0 +1,20 @@
+export default {
+  keySeparator: false,
+  namespaceSeparator: false,
+  contextSeparator: "|",
+  pluralSeparator: "|",
+  createOldCatalogs: false,
+  defaultNamespace: "app",
+  lexers: {
+    ts: [{
+      lexer: "JavascriptLexer",
+      functions: ["t", "translatedError"],
+      functionsNamespace: ["useTranslation", "withTranslation"],
+    }],
+  },
+  locales: ["en-GB"],
+  output: "public/locales/$LOCALE/$NAMESPACE.json",
+  input: ["src/**/*.{ts,tsx}"],
+  sort: true,
+  useKeysAsDefaultValue: true,
+};

package.json

@@ -1,5 +1,6 @@
 {
   "version": "0.0.0",
+  "type": "module",
   "scripts": {
     "dev": "vite",
     "build": "vite build",
@@ -10,7 +11,8 @@
     "prettier:format": "prettier -w src",
     "lint": "yarn lint:types && yarn lint:js",
     "lint:js": "eslint --max-warnings 0 src",
-    "lint:types": "tsc"
+    "lint:types": "tsc",
+    "i18n": "node_modules/i18next-parser/bin/cli.js"
   },
   "dependencies": {
     "@juggle/resize-observer": "^3.3.1",
@@ -38,6 +40,9 @@
     "classnames": "^2.3.1",
     "color-hash": "^2.0.1",
     "events": "^3.3.0",
+    "i18next": "^21.10.0",
+    "i18next-browser-languagedetector": "^6.1.8",
+    "i18next-http-backend": "^1.4.4",
     "matrix-js-sdk": "github:matrix-org/matrix-js-sdk#ce3b72c85031f188a092d1c39806ef7536e65bdd",
     "matrix-widget-api": "^1.0.0",
     "mermaid": "^8.13.8",
@@ -47,6 +52,7 @@
     "re-resizable": "^6.9.0",
     "react": "^17.0.0",
     "react-dom": "^17.0.0",
+    "react-i18next": "^11.18.6",
     "react-json-view": "^1.21.3",
     "react-router": "6",
     "react-router-dom": "^5.2.0",
@@ -71,6 +77,7 @@
     "eslint-plugin-matrix-org": "^0.4.0",
     "eslint-plugin-react": "^7.29.4",
     "eslint-plugin-react-hooks": "^4.5.0",
+    "i18next-parser": "^6.6.0",
     "prettier": "^2.6.2",
     "sass": "^1.42.1",
     "storybook-builder-vite": "^0.1.12",

public/locales/de-DE/app.json

@@ -0,0 +1,4 @@
+{
+  "Invite": "Einladen",
+  "Video call": "Videoanruf"
+}

public/locales/en-GB/app.json

@@ -0,0 +1,135 @@
+{
+  "{{count}} people connected|one": "{{count}} person connected",
+  "{{count}} people connected|other": "{{count}} people connected",
+  "{{displayName}}, your call is now ended": "{{displayName}}, your call is now ended",
+  "{{name}} is presenting": "{{name}} is presenting",
+  "{{name}} is talking…": "{{name}} is talking…",
+  "{{names}}, {{name}}": "{{names}}, {{name}}",
+  "{{roomName}} - Walkie-talkie call": "{{roomName}} - Walkie-talkie call",
+  "<0>Already have an account?</0><1><0>Log in</0> Or <2>Access as a guest</2></1>": "<0>Already have an account?</0><1><0>Log in</0> Or <2>Access as a guest</2></1>",
+  "<0>Create an account</0> Or <2>Access as a guest</2>": "<0>Create an account</0> Or <2>Access as a guest</2>",
+  "<0>Oops, something's gone wrong.</0><1>Submitting debug logs will help us track down the problem.</1>": "<0>Oops, something's gone wrong.</0><1>Submitting debug logs will help us track down the problem.</1>",
+  "<0>Why not finish by setting up a password to keep your account?</0><1>You'll be able to keep your name and set an avatar for use on future calls</1>": "<0>Why not finish by setting up a password to keep your account?</0><1>You'll be able to keep your name and set an avatar for use on future calls</1>",
+  "Accept camera/microphone permissions to join the call.": "Accept camera/microphone permissions to join the call.",
+  "Accept microphone permissions to join the call.": "Accept microphone permissions to join the call.",
+  "Another user on this call is having an issue. In order to better diagnose these issues we'd like to collect a debug log.": "Another user on this call is having an issue. In order to better diagnose these issues we'd like to collect a debug log.",
+  "Audio": "Audio",
+  "Avatar": "Avatar",
+  "By clicking \"Go\", you agree to our <2>Terms and conditions</2>": "By clicking \"Go\", you agree to our <2>Terms and conditions</2>",
+  "By clicking \"Join call now\", you agree to our <2>Terms and conditions</2>": "By clicking \"Join call now\", you agree to our <2>Terms and conditions</2>",
+  "Call link copied": "Call link copied",
+  "Call type menu": "Call type menu",
+  "Camera": "Camera",
+  "Camera {{n}}": "Camera {{n}}",
+  "Camera/microphone permissions needed to join the call.": "Camera/microphone permissions needed to join the call.",
+  "Change layout": "Change layout",
+  "Close": "Close",
+  "Confirm password": "Confirm password",
+  "Connection lost": "Connection lost",
+  "Copied!": "Copied!",
+  "Copy and share this call link": "Copy and share this call link",
+  "Copy call link and join later": "Copy call link and join later",
+  "Create account": "Create account",
+  "Debug log": "Debug log",
+  "Debug log request": "Debug log request",
+  "Description (optional)": "Description (optional)",
+  "Details": "Details",
+  "Developer": "Developer",
+  "Display name": "Display name",
+  "Download debug logs": "Download debug logs",
+  "Entering room…": "Entering room…",
+  "Exit full screen": "Exit full screen",
+  "Fetching group call timed out.": "Fetching group call timed out.",
+  "Freedom": "Freedom",
+  "Full screen": "Full screen",
+  "Go": "Go",
+  "Grid layout menu": "Grid layout menu",
+  "Having trouble? Help us fix it.": "Having trouble? Help us fix it.",
+  "Home": "Home",
+  "Include debug logs": "Include debug logs",
+  "Incompatible versions": "Incompatible versions",
+  "Incompatible versions!": "Incompatible versions!",
+  "Inspector": "Inspector",
+  "Invite": "Invite",
+  "Invite people": "Invite people",
+  "Join call": "Join call",
+  "Join call now": "Join call now",
+  "Join existing call?": "Join existing call?",
+  "Leave": "Leave",
+  "Loading room…": "Loading room…",
+  "Loading…": "Loading…",
+  "Local volume": "Local volume",
+  "Logging in…": "Logging in…",
+  "Login": "Login",
+  "Login to your account": "Login to your account",
+  "Microphone": "Microphone",
+  "Microphone {{n}}": "Microphone {{n}}",
+  "Microphone permissions needed to join the call.": "Microphone permissions needed to join the call.",
+  "More": "More",
+  "More menu": "More menu",
+  "Mute microphone": "Mute microphone",
+  "No": "No",
+  "Not now, return to home screen": "Not now, return to home screen",
+  "Not registered yet? <1>Create an account</1>": "Not registered yet? <1>Create an account</1>",
+  "Not registered yet? <2>Create an account</2>": "Not registered yet? <2>Create an account</2>",
+  "Other users are trying to join this call from incompatible versions. These users should ensure that they have refreshed their browsers:<1>{userLis}</1>": "Other users are trying to join this call from incompatible versions. These users should ensure that they have refreshed their browsers:<1>{userLis}</1>",
+  "Password": "Password",
+  "Passwords must match": "Passwords must match",
+  "Press and hold spacebar to talk": "Press and hold spacebar to talk",
+  "Press and hold spacebar to talk over {{name}}": "Press and hold spacebar to talk over {{name}}",
+  "Press and hold to talk": "Press and hold to talk",
+  "Press and hold to talk over {{name}}": "Press and hold to talk over {{name}}",
+  "Profile": "Profile",
+  "Recaptcha dismissed": "Recaptcha dismissed",
+  "Recaptcha not loaded": "Recaptcha not loaded",
+  "Register": "Register",
+  "Registering…": "Registering…",
+  "Release spacebar key to stop": "Release spacebar key to stop",
+  "Release to stop": "Release to stop",
+  "Remove": "Remove",
+  "Return to home screen": "Return to home screen",
+  "Save": "Save",
+  "Saving…": "Saving…",
+  "Select an option": "Select an option",
+  "Send debug log": "Send debug log",
+  "Send debug logs": "Send debug logs",
+  "Sending debug log…": "Sending debug log…",
+  "Sending…": "Sending…",
+  "Settings": "Settings",
+  "Share screen": "Share screen",
+  "Show call inspector": "Show call inspector",
+  "Sign in": "Sign in",
+  "Sign out": "Sign out",
+  "Spatial audio": "Spatial audio",
+  "Speaker": "Speaker",
+  "Speaker {{n}}": "Speaker {{n}}",
+  "Spotlight": "Spotlight",
+  "Stop sharing screen": "Stop sharing screen",
+  "Submit feedback": "Submit feedback",
+  "Submitting feedback…": "Submitting feedback…",
+  "Take me Home": "Take me Home",
+  "Talk over speaker": "Talk over speaker",
+  "Talking…": "Talking…",
+  "Thanks! We'll get right on it.": "Thanks! We'll get right on it.",
+  "This call already exists, would you like to join?": "This call already exists, would you like to join?",
+  "This site is protected by ReCAPTCHA and the Google <2>Privacy Policy</2> and <6>Terms of Service</6> apply.<9></9>By clicking \"Register\", you agree to our <12>Terms and conditions</12>": "This site is protected by ReCAPTCHA and the Google <2>Privacy Policy</2> and <6>Terms of Service</6> apply.<9></9>By clicking \"Register\", you agree to our <12>Terms and conditions</12>",
+  "This will make a speaker's audio seem as if it is coming from where their tile is positioned on screen. (Experimental feature: this may impact the stability of audio.)": "This will make a speaker's audio seem as if it is coming from where their tile is positioned on screen. (Experimental feature: this may impact the stability of audio.)",
+  "Turn off camera": "Turn off camera",
+  "Turn on camera": "Turn on camera",
+  "Unmute microphone": "Unmute microphone",
+  "User ID": "User ID",
+  "User menu": "User menu",
+  "Username": "Username",
+  "Version: {{version}}": "Version: {{version}}",
+  "Video": "Video",
+  "Video call": "Video call",
+  "Video call name": "Video call name",
+  "Waiting for network": "Waiting for network",
+  "Waiting for other participants…": "Waiting for other participants…",
+  "Walkie-talkie call": "Walkie-talkie call",
+  "Walkie-talkie call name": "Walkie-talkie call name",
+  "WebRTC is not supported or is being blocked in this browser.": "WebRTC is not supported or is being blocked in this browser.",
+  "Yes, join call": "Yes, join call",
+  "You can't talk at the same time": "You can't talk at the same time",
+  "Your recent calls": "Your recent calls"
+}

src/App.tsx

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import React from "react";
+import React, { Suspense } from "react";
 import { BrowserRouter as Router, Switch, Route } from "react-router-dom";
 import * as Sentry from "@sentry/react";
 import { OverlayProvider } from "@react-aria/overlays";
@@ -43,6 +43,7 @@ export default function App({ history }: AppProps) {
 
   return (
     <Router history={history}>
+      <Suspense fallback={null}>
         <ClientProvider>
           <InspectorContextProvider>
             <Sentry.ErrorBoundary fallback={errorPage}>
@@ -71,6 +72,7 @@ export default function App({ history }: AppProps) {
             </Sentry.ErrorBoundary>
           </InspectorContextProvider>
         </ClientProvider>
+      </Suspense>
     </Router>
   );
 }

src/ClientContext.tsx

@@ -27,6 +27,7 @@ import { useHistory } from "react-router-dom";
 import { MatrixClient, ClientEvent } from "matrix-js-sdk/src/client";
 import { MatrixEvent } from "matrix-js-sdk/src/models/event";
 import { logger } from "matrix-js-sdk/src/logger";
+import { useTranslation } from "react-i18next";
 
 import { ErrorView } from "./FullScreenView";
 import {
@@ -35,6 +36,7 @@ import {
   CryptoStoreIntegrityError,
 } from "./matrix-utils";
 import { widget } from "./widget";
+import { translatedError } from "./TranslatedError";
 
 declare global {
   interface Window {
@@ -267,6 +269,8 @@ export const ClientProvider: FC<Props> = ({ children }) => {
     history.push("/");
   }, [history, client]);
 
+  const { t } = useTranslation();
+
   useEffect(() => {
     // To protect against multiple sessions writing to the same storage
     // simultaneously, we send a to-device message that shuts down all other
@@ -287,8 +291,9 @@ export const ClientProvider: FC<Props> = ({ children }) => {
 
           setState((prev) => ({
             ...prev,
-            error: new Error(
+            error: translatedError(
-              "This application has been opened in another tab."
+              "This application has been opened in another tab.",
+              t
             ),
           }));
         }
@@ -306,7 +311,7 @@ export const ClientProvider: FC<Props> = ({ children }) => {
         client?.removeListener(ClientEvent.ToDeviceEvent, onToDeviceEvent);
       };
     }
-  }, [client]);
+  }, [client, t]);
 
   const context = useMemo<ClientState>(
     () => ({

src/Facepile.tsx

@@ -14,10 +14,11 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import React, { HTMLAttributes } from "react";
+import React, { HTMLAttributes, useMemo } from "react";
 import classNames from "classnames";
 import { MatrixClient } from "matrix-js-sdk/src/client";
 import { RoomMember } from "matrix-js-sdk/src/models/room-member";
+import { useTranslation } from "react-i18next";
 
 import styles from "./Facepile.module.css";
 import { Avatar, Size, sizes } from "./Avatar";
@@ -44,13 +45,25 @@ export function Facepile({
   size = Size.XS,
   ...rest
 }: Props) {
+  const { t } = useTranslation();
+
   const _size = sizes.get(size);
   const _overlap = overlapMap[size];
 
+  const title = useMemo(() => {
+    return participants.reduce<string | null>(
+      (prev, curr) =>
+        prev === null
+          ? curr.name
+          : t("{{names}}, {{name}}", { names: prev, name: curr.name }),
+      null
+    ) as string;
+  }, [participants, t]);
+
   return (
     <div
       className={classNames(styles.facepile, styles[size], className)}
-      title={participants.map((member) => member.name).join(", ")}
+      title={title}
       style={{
         width:
           Math.min(participants.length, max + 1) * (_size - _overlap) +

src/FullScreenView.tsx

@@ -1,12 +1,14 @@
 import React, { ReactNode, useCallback, useEffect } from "react";
 import { useLocation } from "react-router-dom";
 import classNames from "classnames";
+import { Trans, useTranslation } from "react-i18next";
 
 import { Header, HeaderLogo, LeftNav, RightNav } from "./Header";
 import { LinkButton, Button } from "./button";
 import { useSubmitRageshake } from "./settings/submit-rageshake";
 import { ErrorMessage } from "./input/Input";
 import styles from "./FullScreenView.module.css";
+import { translatedError, TranslatedError } from "./TranslatedError";
 
 interface FullScreenViewProps {
   className?: string;
@@ -35,6 +37,7 @@ interface ErrorViewProps {
 
 export function ErrorView({ error }: ErrorViewProps) {
   const location = useLocation();
+  const { t } = useTranslation();
 
   useEffect(() => {
     console.error(error);
@@ -47,7 +50,11 @@ export function ErrorView({ error }: ErrorViewProps) {
   return (
     <FullScreenView>
       <h1>Error</h1>
-      <p>{error.message}</p>
+      <p>
+        {error instanceof TranslatedError
+          ? error.translatedMessage
+          : error.message}
+      </p>
       {location.pathname === "/" ? (
         <Button
           size="lg"
@@ -55,7 +62,7 @@ export function ErrorView({ error }: ErrorViewProps) {
           className={styles.homeLink}
           onPress={onReload}
         >
-          Return to home screen
+          {t("Return to home screen")}
         </Button>
       ) : (
         <LinkButton
@@ -64,7 +71,7 @@ export function ErrorView({ error }: ErrorViewProps) {
           className={styles.homeLink}
           to="/"
         >
-          Return to home screen
+          {t("Return to home screen")}
         </LinkButton>
       )}
     </FullScreenView>
@@ -72,6 +79,7 @@ export function ErrorView({ error }: ErrorViewProps) {
 }
 
 export function CrashView() {
+  const { t } = useTranslation();
   const { submitRageshake, sending, sent, error } = useSubmitRageshake();
 
   const sendDebugLogs = useCallback(() => {
@@ -85,11 +93,11 @@ export function CrashView() {
     window.location.href = "/";
   }, []);
 
-  let logsComponent;
+  let logsComponent: JSX.Element | null = null;
   if (sent) {
-    logsComponent = <div>Thanks! We'll get right on it.</div>;
+    logsComponent = <div>{t("Thanks! We'll get right on it.")}</div>;
   } else if (sending) {
-    logsComponent = <div>Sending...</div>;
+    logsComponent = <div>{t("Sending…")}</div>;
   } else {
     logsComponent = (
       <Button
@@ -98,33 +106,39 @@ export function CrashView() {
         onPress={sendDebugLogs}
         className={styles.wideButton}
       >
-        Send debug logs
+        {t("Send debug logs")}
       </Button>
     );
   }
 
   return (
     <FullScreenView>
+      <Trans>
         <h1>Oops, something's gone wrong.</h1>
         <p>Submitting debug logs will help us track down the problem.</p>
+      </Trans>
       <div className={styles.sendLogsSection}>{logsComponent}</div>
-      {error && <ErrorMessage>Couldn't send debug logs!</ErrorMessage>}
+      {error && (
+        <ErrorMessage error={translatedError("Couldn't send debug logs!", t)} />
+      )}
       <Button
         size="lg"
         variant="default"
         className={styles.wideButton}
         onPress={onReload}
       >
-        Return to home screen
+        {t("Return to home screen")}
       </Button>
     </FullScreenView>
   );
 }
 
 export function LoadingView() {
+  const { t } = useTranslation();
+
   return (
     <FullScreenView>
-      <h1>Loading...</h1>
+      <h1>{t("Loading…")}</h1>
     </FullScreenView>
   );
 }

src/Header.tsx

@@ -4,6 +4,7 @@ import { Link } from "react-router-dom";
 import { useButton } from "@react-aria/button";
 import { AriaButtonProps } from "@react-types/button";
 import { Room } from "matrix-js-sdk/src/models/room";
+import { useTranslation } from "react-i18next";
 
 import styles from "./Header.module.css";
 import { useModalTriggerState } from "./Modal";
@@ -156,6 +157,7 @@ export function VersionMismatchWarning({
   users,
   room,
 }: VersionMismatchWarningProps) {
+  const { t } = useTranslation();
   const { modalState, modalProps } = useModalTriggerState();
 
   const onDetailsClick = useCallback(() => {
@@ -166,9 +168,9 @@ export function VersionMismatchWarning({
 
   return (
     <span className={styles.versionMismatchWarning}>
-      Incomaptible versions!
+      {t("Incompatible versions!")}
       <Button variant="link" onClick={onDetailsClick}>
-        Details
+        {t("Details")}
       </Button>
       {modalState.isOpen && (
         <IncompatibleVersionModal userIds={users} room={room} {...modalProps} />

src/IncompatibleVersionModal.tsx

@@ -15,7 +15,8 @@ limitations under the License.
 */
 
 import { Room } from "matrix-js-sdk/src/models/room";
-import React from "react";
+import React, { useMemo } from "react";
+import { Trans, useTranslation } from "react-i18next";
 
 import { Modal, ModalContent } from "./Modal";
 import { Body } from "./typography/Typography";
@@ -30,17 +31,21 @@ export const IncompatibleVersionModal: React.FC<Props> = ({
   room,
   ...rest
 }) => {
-  const userLis = Array.from(userIds).map((u) => (
+  const { t } = useTranslation();
-    <li>{room.getMember(u).name}</li>
+  const userLis = useMemo(
-  ));
+    () => [...userIds].map((u) => <li>{room.getMember(u)?.name ?? u}</li>),
+    [userIds, room]
+  );
 
   return (
-    <Modal title="Incompatible Versions" isDismissable {...rest}>
+    <Modal title={t("Incompatible versions")} isDismissable {...rest}>
       <ModalContent>
         <Body>
+          <Trans>
             Other users are trying to join this call from incompatible versions.
             These users should ensure that they have refreshed their browsers:
             <ul>{userLis}</ul>
+          </Trans>
         </Body>
       </ModalContent>
     </Modal>

src/Modal.tsx

@@ -33,6 +33,7 @@ import { FocusScope } from "@react-aria/focus";
 import { ButtonAria, useButton } from "@react-aria/button";
 import classNames from "classnames";
 import { AriaDialogProps } from "@react-types/dialog";
+import { useTranslation } from "react-i18next";
 
 import { ReactComponent as CloseIcon } from "./icons/Close.svg";
 import styles from "./Modal.module.css";
@@ -53,6 +54,7 @@ export function Modal({
   onClose,
   ...rest
 }: ModalProps) {
+  const { t } = useTranslation();
   const modalRef = useRef();
   const { overlayProps, underlayProps } = useOverlay(
     { ...rest, onClose },
@@ -90,6 +92,7 @@ export function Modal({
                 {...closeButtonProps}
                 ref={closeButtonRef}
                 className={styles.closeButton}
+                title={t("Close")}
               >
                 <CloseIcon />
               </button>

src/SequenceDiagramViewerPage.tsx

@@ -15,6 +15,7 @@ limitations under the License.
 */
 
 import React, { useCallback, useState } from "react";
+import { useTranslation } from "react-i18next";
 
 import {
   SequenceDiagramViewer,
@@ -30,7 +31,8 @@ interface DebugLog {
 }
 
 export function SequenceDiagramViewerPage() {
-  usePageTitle("Inspector");
+  const { t } = useTranslation();
+  usePageTitle(t("Inspector"));
 
   const [debugLog, setDebugLog] = useState<DebugLog>();
   const [selectedUserId, setSelectedUserId] = useState<string>();
@@ -49,7 +51,7 @@ export function SequenceDiagramViewerPage() {
           type="file"
           id="debugLog"
           name="debugLog"
-          label="Debug Log"
+          label={t("Debug log")}
           onChange={onChangeDebugLog}
         />
       </FieldRow>

src/TranslatedError.ts

@@ -0,0 +1,41 @@
+/*
+Copyright 2022 New Vector Ltd
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import i18n from "i18next";
+
+/**
+ * An error with messages in both English and the user's preferred language.
+ */
+// Abstract to force consumers to use the function below rather than calling the
+// constructor directly
+export abstract class TranslatedError extends Error {
+  /**
+   * The error message in the user's preferred language.
+   */
+  public readonly translatedMessage: string;
+
+  public constructor(messageKey: string, translationFn: typeof i18n.t) {
+    super(translationFn(messageKey, { lng: "en-GB" }));
+    this.translatedMessage = translationFn(messageKey);
+  }
+}
+
+class TranslatedErrorImpl extends TranslatedError {}
+
+// i18next-parser can't detect calls to a constructor, so we expose a bare
+// function instead
+export const translatedError = (messageKey: string, t: typeof i18n.t) =>
+  new TranslatedErrorImpl(messageKey, t);

src/UrlParams.ts

@@ -17,7 +17,7 @@ limitations under the License.
 import { useMemo } from "react";
 import { useLocation } from "react-router-dom";
 
-export interface RoomParams {
+export interface UrlParams {
   roomAlias: string | null;
   roomId: string | null;
   viaServers: string[];
@@ -39,25 +39,27 @@ export interface RoomParams {
   displayName: string | null;
   // The device's ID (only used in Matroska mode)
   deviceId: string | null;
+  // The BCP 47 code of the language the app should use
+  lang: string | null;
 }
 
 /**
- * Gets the room parameters for the current URL.
+ * Gets the app parameters for the current URL.
- * @param {string} query The URL query string
+ * @param query The URL query string
- * @param {string} fragment The URL fragment string
+ * @param fragment The URL fragment string
- * @returns {RoomParams} The room parameters encoded in the URL
+ * @returns The app parameters encoded in the URL
  */
-export const getRoomParams = (
+export const getUrlParams = (
   query: string = window.location.search,
   fragment: string = window.location.hash
-): RoomParams => {
+): UrlParams => {
   const fragmentQueryStart = fragment.indexOf("?");
   const fragmentParams = new URLSearchParams(
     fragmentQueryStart === -1 ? "" : fragment.substring(fragmentQueryStart)
   );
   const queryParams = new URLSearchParams(query);
 
-  // Normally, room params should be encoded in the fragment so as to avoid
+  // Normally, URL params should be encoded in the fragment so as to avoid
   // leaking them to the server. However, we also check the normal query
   // string for backwards compatibility with versions that only used that.
   const hasParam = (name: string): boolean =>
@@ -87,14 +89,15 @@ export const getRoomParams = (
     userId: getParam("userId"),
     displayName: getParam("displayName"),
     deviceId: getParam("deviceId"),
+    lang: getParam("lang"),
   };
 };
 
 /**
- * Hook to simplify use of getRoomParams.
+ * Hook to simplify use of getUrlParams.
- * @returns {RoomParams} The room parameters for the current URL
+ * @returns The app parameters for the current URL
  */
-export const useRoomParams = (): RoomParams => {
+export const useUrlParams = (): UrlParams => {
   const { hash, search } = useLocation();
-  return useMemo(() => getRoomParams(search, hash), [search, hash]);
+  return useMemo(() => getUrlParams(search, hash), [search, hash]);
 };

src/UserMenu.tsx

@@ -1,6 +1,7 @@
-import React, { useMemo } from "react";
+import React, { useCallback, useMemo } from "react";
 import { Item } from "@react-stately/collections";
 import { useLocation } from "react-router-dom";
+import { useTranslation } from "react-i18next";
 
 import { Button, LinkButton } from "./button";
 import { PopoverMenuTrigger } from "./popover/PopoverMenu";
@@ -30,6 +31,7 @@ export function UserMenu({
   avatarUrl,
   onAction,
 }: UserMenuProps) {
+  const { t } = useTranslation();
   const location = useLocation();
 
   const items = useMemo(() => {
@@ -45,7 +47,7 @@ export function UserMenu({
       if (isPasswordlessUser && !preventNavigation) {
         arr.push({
           key: "login",
-          label: "Sign In",
+          label: t("Sign in"),
           icon: LoginIcon,
         });
       }
@@ -53,14 +55,16 @@ export function UserMenu({
       if (!isPasswordlessUser && !preventNavigation) {
         arr.push({
           key: "logout",
-          label: "Sign Out",
+          label: t("Sign out"),
           icon: LogoutIcon,
         });
       }
     }
 
     return arr;
-  }, [isAuthenticated, isPasswordlessUser, displayName, preventNavigation]);
+  }, [isAuthenticated, isPasswordlessUser, displayName, preventNavigation, t]);
+
+  const tooltip = useCallback(() => t("Profile"), [t]);
 
   if (!isAuthenticated) {
     return (
@@ -72,7 +76,7 @@ export function UserMenu({
 
   return (
     <PopoverMenuTrigger placement="bottom right">
-      <TooltipTrigger tooltip={() => "Profile"} placement="bottom left">
+      <TooltipTrigger tooltip={tooltip} placement="bottom left">
         <Button variant="icon" className={styles.userButton}>
           {isAuthenticated && (!isPasswordlessUser || avatarUrl) ? (
             <Avatar
@@ -87,7 +91,7 @@ export function UserMenu({
         </Button>
       </TooltipTrigger>
       {(props) => (
-        <Menu {...props} label="User menu" onAction={onAction}>
+        <Menu {...props} label={t("User menu")} onAction={onAction}>
           {items.map(({ key, icon: Icon, label }) => (
             <Item key={key} textValue={label}>
               <Icon width={24} height={24} className={styles.menuIcon} />

src/auth/LoginPage.tsx

@@ -23,6 +23,7 @@ import React, {
   useMemo,
 } from "react";
 import { useHistory, useLocation, Link } from "react-router-dom";
+import { Trans, useTranslation } from "react-i18next";
 
 import { ReactComponent as Logo } from "../icons/LogoLarge.svg";
 import { useClient } from "../ClientContext";
@@ -34,7 +35,8 @@ import { useInteractiveLogin } from "./useInteractiveLogin";
 import { usePageTitle } from "../usePageTitle";
 
 export const LoginPage: FC = () => {
-  usePageTitle("Login");
+  const { t } = useTranslation();
+  usePageTitle(t("Login"));
 
   const { setClient } = useClient();
   const login = useInteractiveLogin();
@@ -93,8 +95,8 @@ export const LoginPage: FC = () => {
                 <InputField
                   type="text"
                   ref={usernameRef}
-                  placeholder="Username"
+                  placeholder={t("Username")}
-                  label="Username"
+                  label={t("Username")}
                   autoCorrect="off"
                   autoCapitalize="none"
                   prefix="@"
@@ -105,18 +107,18 @@ export const LoginPage: FC = () => {
                 <InputField
                   type="password"
                   ref={passwordRef}
-                  placeholder="Password"
+                  placeholder={t("Password")}
-                  label="Password"
+                  label={t("Password")}
                 />
               </FieldRow>
               {error && (
                 <FieldRow>
-                  <ErrorMessage>{error.message}</ErrorMessage>
+                  <ErrorMessage error={error} />
                 </FieldRow>
               )}
               <FieldRow>
                 <Button type="submit" disabled={loading}>
-                  {loading ? "Logging in..." : "Login"}
+                  {loading ? t("Logging in…") : t("Login")}
                 </Button>
               </FieldRow>
             </form>
@@ -124,9 +126,11 @@ export const LoginPage: FC = () => {
           <div className={styles.authLinks}>
             <p>Not registered yet?</p>
             <p>
+              <Trans>
                 <Link to="/register">Create an account</Link>
                 {" Or "}
                 <Link to="/">Access as a guest</Link>
+              </Trans>
             </p>
           </div>
         </div>

src/auth/RegisterPage.tsx

@@ -26,6 +26,7 @@ import React, {
 import { useHistory, useLocation } from "react-router-dom";
 import { captureException } from "@sentry/react";
 import { sleep } from "matrix-js-sdk/src/utils";
+import { Trans, useTranslation } from "react-i18next";
 
 import { FieldRow, InputField, ErrorMessage } from "../input/Input";
 import { Button } from "../button";
@@ -40,7 +41,8 @@ import { Caption, Link } from "../typography/Typography";
 import { usePageTitle } from "../usePageTitle";
 
 export const RegisterPage: FC = () => {
-  usePageTitle("Register");
+  const { t } = useTranslation();
+  usePageTitle(t("Register"));
 
   const { loading, isAuthenticated, isPasswordlessUser, client, setClient } =
     useClient();
@@ -126,11 +128,11 @@ export const RegisterPage: FC = () => {
 
   useEffect(() => {
     if (password && passwordConfirmation && password !== passwordConfirmation) {
-      confirmPasswordRef.current?.setCustomValidity("Passwords must match");
+      confirmPasswordRef.current?.setCustomValidity(t("Passwords must match"));
     } else {
       confirmPasswordRef.current?.setCustomValidity("");
     }
-  }, [password, passwordConfirmation]);
+  }, [password, passwordConfirmation, t]);
 
   useEffect(() => {
     if (!loading && isAuthenticated && !isPasswordlessUser && !registering) {
@@ -154,8 +156,8 @@ export const RegisterPage: FC = () => {
                 <InputField
                   type="text"
                   name="userName"
-                  placeholder="Username"
+                  placeholder={t("Username")}
-                  label="Username"
+                  label={t("Username")}
                   autoCorrect="off"
                   autoCapitalize="none"
                   prefix="@"
@@ -171,8 +173,8 @@ export const RegisterPage: FC = () => {
                     setPassword(e.target.value)
                   }
                   value={password}
-                  placeholder="Password"
+                  placeholder={t("Password")}
-                  label="Password"
+                  label={t("Password")}
                 />
               </FieldRow>
               <FieldRow>
@@ -184,12 +186,13 @@ export const RegisterPage: FC = () => {
                     setPasswordConfirmation(e.target.value)
                   }
                   value={passwordConfirmation}
-                  placeholder="Confirm Password"
+                  placeholder={t("Confirm password")}
-                  label="Confirm Password"
+                  label={t("Confirm password")}
                   ref={confirmPasswordRef}
                 />
               </FieldRow>
               <Caption>
+                <Trans>
                   This site is protected by ReCAPTCHA and the Google{" "}
                   <Link href="https://www.google.com/policies/privacy/">
                     Privacy Policy
@@ -202,27 +205,30 @@ export const RegisterPage: FC = () => {
                   <br />
                   By clicking "Register", you agree to our{" "}
                   <Link href={privacyPolicyUrl}>Terms and conditions</Link>
+                </Trans>
               </Caption>
               {error && (
                 <FieldRow>
-                  <ErrorMessage>{error.message}</ErrorMessage>
+                  <ErrorMessage error={error} />
                 </FieldRow>
               )}
               <FieldRow>
                 <Button type="submit" disabled={registering}>
-                  {registering ? "Registering..." : "Register"}
+                  {registering ? t("Registering…") : t("Register")}
                 </Button>
               </FieldRow>
               <div id={recaptchaId} />
             </form>
           </div>
           <div className={styles.authLinks}>
+            <Trans>
               <p>Already have an account?</p>
               <p>
                 <Link to="/login">Log in</Link>
                 {" Or "}
                 <Link to="/">Access as a guest</Link>
               </p>
+            </Trans>
           </div>
         </div>
       </div>

src/auth/useRecaptcha.ts

@@ -16,6 +16,9 @@ limitations under the License.
 
 import { useEffect, useCallback, useRef, useState } from "react";
 import { randomString } from "matrix-js-sdk/src/randomstring";
+import { useTranslation } from "react-i18next";
+
+import { translatedError } from "../TranslatedError";
 
 declare global {
   interface Window {
@@ -32,6 +35,7 @@ interface RecaptchaPromiseRef {
 }
 
 export const useRecaptcha = (sitekey: string) => {
+  const { t } = useTranslation();
   const [recaptchaId] = useState(() => randomString(16));
   const promiseRef = useRef<RecaptchaPromiseRef>();
 
@@ -71,14 +75,14 @@ export const useRecaptcha = (sitekey: string) => {
 
     if (!window.grecaptcha) {
       console.log("Recaptcha not loaded");
-      return Promise.reject(new Error("Recaptcha not loaded"));
+      return Promise.reject(translatedError("Recaptcha not loaded", t));
     }
 
     return new Promise((resolve, reject) => {
       const observer = new MutationObserver((mutationsList) => {
         for (const item of mutationsList) {
           if ((item.target as HTMLElement)?.style?.visibility !== "visible") {
-            reject(new Error("Recaptcha dismissed"));
+            reject(translatedError("Recaptcha dismissed", t));
             observer.disconnect();
             return;
           }
@@ -108,7 +112,7 @@ export const useRecaptcha = (sitekey: string) => {
         });
       }
     });
-  }, [sitekey]);
+  }, [sitekey, t]);
 
   const reset = useCallback(() => {
     window.grecaptcha?.reset();

src/button/Button.tsx

@@ -18,6 +18,7 @@ import { PressEvent } from "@react-types/shared";
 import classNames from "classnames";
 import { useButton } from "@react-aria/button";
 import { mergeProps, useObjectRef } from "@react-aria/utils";
+import { useTranslation } from "react-i18next";
 
 import styles from "./Button.module.css";
 import { ReactComponent as MicIcon } from "../icons/Mic.svg";
@@ -142,9 +143,11 @@ export function MicButton({
   // TODO: add all props for <Button>
   [index: string]: unknown;
 }) {
+  const { t } = useTranslation();
+
   return (
     <TooltipTrigger
-      tooltip={() => (muted ? "Unmute microphone" : "Mute microphone")}
+      tooltip={() => (muted ? t("Unmute microphone") : t("Mute microphone"))}
     >
       <Button variant="toolbar" {...rest} off={muted}>
         {muted ? <MuteMicIcon /> : <MicIcon />}
@@ -161,9 +164,11 @@ export function VideoButton({
   // TODO: add all props for <Button>
   [index: string]: unknown;
 }) {
+  const { t } = useTranslation();
+
   return (
     <TooltipTrigger
-      tooltip={() => (muted ? "Turn on camera" : "Turn off camera")}
+      tooltip={() => (muted ? t("Turn on camera") : t("Turn off camera"))}
     >
       <Button variant="toolbar" {...rest} off={muted}>
         {muted ? <DisableVideoIcon /> : <VideoIcon />}
@@ -182,9 +187,11 @@ export function ScreenshareButton({
   // TODO: add all props for <Button>
   [index: string]: unknown;
 }) {
+  const { t } = useTranslation();
+
   return (
     <TooltipTrigger
-      tooltip={() => (enabled ? "Stop sharing screen" : "Share screen")}
+      tooltip={() => (enabled ? t("Stop sharing screen") : t("Share screen"))}
     >
       <Button variant="toolbarSecondary" {...rest} on={enabled}>
         <ScreenshareIcon />
@@ -201,8 +208,11 @@ export function HangupButton({
   // TODO: add all props for <Button>
   [index: string]: unknown;
 }) {
+  const { t } = useTranslation();
+  const tooltip = useCallback(() => t("Leave"), [t]);
+
   return (
-    <TooltipTrigger tooltip={() => "Leave"}>
+    <TooltipTrigger tooltip={tooltip}>
       <Button
         variant="toolbar"
         className={classNames(styles.hangupButton, className)}
@@ -222,8 +232,11 @@ export function SettingsButton({
   // TODO: add all props for <Button>
   [index: string]: unknown;
 }) {
+  const { t } = useTranslation();
+  const tooltip = useCallback(() => t("Settings"), [t]);
+
   return (
-    <TooltipTrigger tooltip={() => "Settings"}>
+    <TooltipTrigger tooltip={tooltip}>
       <Button variant="toolbar" {...rest}>
         <SettingsIcon />
       </Button>
@@ -239,8 +252,11 @@ export function InviteButton({
   // TODO: add all props for <Button>
   [index: string]: unknown;
 }) {
+  const { t } = useTranslation();
+  const tooltip = useCallback(() => t("Invite"), [t]);
+
   return (
-    <TooltipTrigger tooltip={() => "Invite"}>
+    <TooltipTrigger tooltip={tooltip}>
       <Button variant="toolbar" {...rest}>
         <AddUserIcon />
       </Button>
@@ -256,8 +272,11 @@ interface AudioButtonProps extends Omit<Props, "variant"> {
 }
 
 export function AudioButton({ volume, ...rest }: AudioButtonProps) {
+  const { t } = useTranslation();
+  const tooltip = useCallback(() => t("Local volume"), [t]);
+
   return (
-    <TooltipTrigger tooltip={() => "Local volume"}>
+    <TooltipTrigger tooltip={tooltip}>
       <Button variant="icon" {...rest}>
         <VolumeIcon volume={volume} />
       </Button>
@@ -273,12 +292,13 @@ export function FullscreenButton({
   fullscreen,
   ...rest
 }: FullscreenButtonProps) {
-  const getTooltip = useCallback(() => {
+  const { t } = useTranslation();
-    return fullscreen ? "Exit full screen" : "Full screen";
+  const tooltip = useCallback(() => {
-  }, [fullscreen]);
+    return fullscreen ? t("Exit full screen") : t("Full screen");
+  }, [fullscreen, t]);
 
   return (
-    <TooltipTrigger tooltip={getTooltip}>
+    <TooltipTrigger tooltip={tooltip}>
       <Button variant="icon" {...rest}>
         {fullscreen ? <FullscreenExit /> : <Fullscreen />}
       </Button>

src/button/CopyButton.tsx

@@ -15,6 +15,7 @@ limitations under the License.
 */
 
 import React from "react";
+import { useTranslation } from "react-i18next";
 import useClipboard from "react-use-clipboard";
 
 import { ReactComponent as CheckIcon } from "../icons/Check.svg";
@@ -36,6 +37,7 @@ export function CopyButton({
   copiedMessage,
   ...rest
 }: Props) {
+  const { t } = useTranslation();
   const [isCopied, setCopied] = useClipboard(value, { successDuration: 3000 });
 
   return (
@@ -49,7 +51,7 @@ export function CopyButton({
     >
       {isCopied ? (
         <>
-          {variant !== "icon" && <span>{copiedMessage || "Copied!"}</span>}
+          {variant !== "icon" && <span>{copiedMessage || t("Copied!")}</span>}
           <CheckIcon />
         </>
       ) : (

src/home/CallTypeDropdown.tsx

@@ -16,6 +16,7 @@ limitations under the License.
 
 import React, { FC } from "react";
 import { Item } from "@react-stately/collections";
+import { useTranslation } from "react-i18next";
 
 import { Headline } from "../typography/Typography";
 import { Button } from "../button";
@@ -39,25 +40,29 @@ interface Props {
 }
 
 export const CallTypeDropdown: FC<Props> = ({ callType, setCallType }) => {
+  const { t } = useTranslation();
+
   return (
     <PopoverMenuTrigger placement="bottom">
       <Button variant="dropdown" className={commonStyles.headline}>
         <Headline className={styles.label}>
-          {callType === CallType.Video ? "Video call" : "Walkie-talkie call"}
+          {callType === CallType.Video
+            ? t("Video call")
+            : t("Walkie-talkie call")}
         </Headline>
       </Button>
       {(props: JSX.IntrinsicAttributes) => (
-        <Menu {...props} label="Call type menu" onAction={setCallType}>
+        <Menu {...props} label={t("Call type menu")} onAction={setCallType}>
-          <Item key={CallType.Video} textValue="Video call">
+          <Item key={CallType.Video} textValue={t("Video call")}>
             <VideoIcon />
-            <span>Video call</span>
+            <span>{t("Video call")}</span>
             {callType === CallType.Video && (
               <CheckIcon className={menuStyles.checkIcon} />
             )}
           </Item>
-          <Item key={CallType.Radio} textValue="Walkie-talkie call">
+          <Item key={CallType.Radio} textValue={t("Walkie-talkie call")}>
             <MicIcon />
-            <span>Walkie-talkie call</span>
+            <span>{t("Walkie-talkie call")}</span>
             {callType === CallType.Radio && (
               <CheckIcon className={menuStyles.checkIcon} />
             )}

src/home/HomePage.tsx

@@ -15,6 +15,7 @@ limitations under the License.
 */
 
 import React from "react";
+import { useTranslation } from "react-i18next";
 
 import { useClient } from "../ClientContext";
 import { ErrorView, LoadingView } from "../FullScreenView";
@@ -23,7 +24,8 @@ import { RegisteredView } from "./RegisteredView";
 import { usePageTitle } from "../usePageTitle";
 
 export function HomePage() {
-  usePageTitle("Home");
+  const { t } = useTranslation();
+  usePageTitle(t("Home"));
 
   const { isAuthenticated, isPasswordlessUser, loading, error, client } =
     useClient();

src/home/JoinExistingCallModal.tsx

@@ -16,6 +16,7 @@ limitations under the License.
 
 import React from "react";
 import { PressEvent } from "@react-types/shared";
+import { useTranslation } from "react-i18next";
 
 import { Modal, ModalContent } from "../Modal";
 import { Button } from "../button";
@@ -29,13 +30,15 @@ interface Props {
   [index: string]: unknown;
 }
 export function JoinExistingCallModal({ onJoin, onClose, ...rest }: Props) {
+  const { t } = useTranslation();
+
   return (
-    <Modal title="Join existing call?" isDismissable {...rest}>
+    <Modal title={t("Join existing call?")} isDismissable {...rest}>
       <ModalContent>
-        <p>This call already exists, would you like to join?</p>
+        <p>{t("This call already exists, would you like to join?")}</p>
         <FieldRow rightAlign className={styles.buttons}>
-          <Button onPress={onClose}>No</Button>
+          <Button onPress={onClose}>{t("No")}</Button>
-          <Button onPress={onJoin}>Yes, join call</Button>
+          <Button onPress={onJoin}>{t("Yes, join call")}</Button>
         </FieldRow>
       </ModalContent>
     </Modal>

src/home/RegisteredView.tsx

@@ -22,6 +22,7 @@ import React, {
 } from "react";
 import { useHistory } from "react-router-dom";
 import { MatrixClient } from "matrix-js-sdk/src/client";
+import { useTranslation } from "react-i18next";
 
 import { createRoom, roomAliasLocalpartFromRoomName } from "../matrix-utils";
 import { useGroupCallRooms } from "./useGroupCallRooms";
@@ -48,6 +49,7 @@ export function RegisteredView({ client, isPasswordlessUser }: Props) {
   const [loading, setLoading] = useState(false);
   const [error, setError] = useState<Error>();
   const history = useHistory();
+  const { t } = useTranslation();
   const { modalState, modalProps } = useModalTriggerState();
 
   const onSubmit: FormEventHandler<HTMLFormElement> = useCallback(
@@ -93,7 +95,9 @@ export function RegisteredView({ client, isPasswordlessUser }: Props) {
   }, [history, existingRoomId]);
 
   const callNameLabel =
-    callType === CallType.Video ? "Video call name" : "Walkie-talkie call name";
+    callType === CallType.Video
+      ? t("Video call name")
+      : t("Walkie-talkie call name");
 
   return (
     <>
@@ -127,19 +131,19 @@ export function RegisteredView({ client, isPasswordlessUser }: Props) {
                 className={styles.button}
                 disabled={loading}
               >
-                {loading ? "Loading..." : "Go"}
+                {loading ? t("Loading…") : t("Go")}
               </Button>
             </FieldRow>
             {error && (
               <FieldRow className={styles.fieldRow}>
-                <ErrorMessage>{error.message}</ErrorMessage>
+                <ErrorMessage error={error} />
               </FieldRow>
             )}
           </Form>
           {recentRooms.length > 0 && (
             <>
               <Title className={styles.recentCallsTitle}>
-                Your recent Calls
+                {t("Your recent calls")}
               </Title>
               <CallList rooms={recentRooms} client={client} disableFacepile />
             </>

src/home/UnauthenticatedView.tsx

@@ -17,6 +17,7 @@ limitations under the License.
 import React, { FC, useCallback, useState, FormEventHandler } from "react";
 import { useHistory } from "react-router-dom";
 import { randomString } from "matrix-js-sdk/src/randomstring";
+import { Trans, useTranslation } from "react-i18next";
 
 import { useClient } from "../ClientContext";
 import { Header, HeaderLogo, LeftNav, RightNav } from "../Header";
@@ -47,6 +48,7 @@ export const UnauthenticatedView: FC = () => {
   const { modalState, modalProps } = useModalTriggerState();
   const [onFinished, setOnFinished] = useState<() => void>();
   const history = useHistory();
+  const { t } = useTranslation();
 
   const onSubmit: FormEventHandler<HTMLFormElement> = useCallback(
     (e) => {
@@ -105,7 +107,9 @@ export const UnauthenticatedView: FC = () => {
   );
 
   const callNameLabel =
-    callType === CallType.Video ? "Video call name" : "Walkie-talkie call name";
+    callType === CallType.Video
+      ? t("Video call name")
+      : t("Walkie-talkie call name");
 
   return (
     <>
@@ -137,24 +141,26 @@ export const UnauthenticatedView: FC = () => {
               <InputField
                 id="displayName"
                 name="displayName"
-                label="Display Name"
+                label={t("Display name")}
-                placeholder="Display Name"
+                placeholder={t("Display name")}
                 type="text"
                 required
                 autoComplete="off"
               />
             </FieldRow>
             <Caption>
+              <Trans>
                 By clicking "Go", you agree to our{" "}
                 <Link href={privacyPolicyUrl}>Terms and conditions</Link>
+              </Trans>
             </Caption>
             {error && (
               <FieldRow>
-                <ErrorMessage>{error.message}</ErrorMessage>
+                <ErrorMessage error={error} />
               </FieldRow>
             )}
             <Button type="submit" size="lg" disabled={loading}>
-              {loading ? "Loading..." : "Go"}
+              {loading ? t("Loading…") : t("Go")}
             </Button>
             <div id={recaptchaId} />
           </Form>
@@ -162,14 +168,16 @@ export const UnauthenticatedView: FC = () => {
         <footer className={styles.footer}>
           <Body className={styles.mobileLoginLink}>
             <Link color="primary" to="/login">
-              Login to your account
+              {t("Login to your account")}
             </Link>
           </Body>
           <Body>
+            <Trans>
               Not registered yet?{" "}
               <Link color="primary" to="/register">
                 Create an account
               </Link>
+            </Trans>
           </Body>
         </footer>
       </div>

src/input/AvatarInputField.tsx

@@ -20,6 +20,7 @@ import { useCallback } from "react";
 import { useState } from "react";
 import { forwardRef } from "react";
 import classNames from "classnames";
+import { useTranslation } from "react-i18next";
 
 import { Avatar, Size } from "../Avatar";
 import { Button } from "../button";
@@ -39,6 +40,8 @@ export const AvatarInputField = forwardRef<HTMLInputElement, Props>(
     { id, label, className, avatarUrl, displayName, onRemoveAvatar, ...rest },
     ref
   ) => {
+    const { t } = useTranslation();
+
     const [removed, setRemoved] = useState(false);
     const [objUrl, setObjUrl] = useState<string>(null);
 
@@ -97,7 +100,7 @@ export const AvatarInputField = forwardRef<HTMLInputElement, Props>(
             variant="icon"
             onPress={onPressRemoveAvatar}
           >
-            Remove
+            {t("Remove")}
           </Button>
         )}
       </div>

src/input/Input.tsx

@@ -14,11 +14,12 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import React, { ChangeEvent, forwardRef, ReactNode } from "react";
+import React, { ChangeEvent, FC, forwardRef, ReactNode } from "react";
 import classNames from "classnames";
 
 import styles from "./Input.module.css";
 import { ReactComponent as CheckIcon } from "../icons/Check.svg";
+import { TranslatedError } from "../TranslatedError";
 
 interface FieldRowProps {
   children: ReactNode;
@@ -140,10 +141,12 @@ export const InputField = forwardRef<
   }
 );
 
-export function ErrorMessage({
+interface ErrorMessageProps {
-  children,
+  error: Error;
-}: {
-  children: ReactNode;
-}): JSX.Element {
-  return <p className={styles.errorMessage}>{children}</p>;
 }
+
+export const ErrorMessage: FC<ErrorMessageProps> = ({ error }) => (
+  <p className={styles.errorMessage}>
+    {error instanceof TranslatedError ? error.translatedMessage : error.message}
+  </p>
+);

src/input/SelectInput.tsx

@@ -19,6 +19,7 @@ import { AriaSelectOptions, HiddenSelect, useSelect } from "@react-aria/select";
 import { useButton } from "@react-aria/button";
 import { useSelectState } from "@react-stately/select";
 import classNames from "classnames";
+import { useTranslation } from "react-i18next";
 
 import { Popover } from "../popover/Popover";
 import { ListBox } from "../ListBox";
@@ -30,6 +31,7 @@ interface Props extends AriaSelectOptions<object> {
 }
 
 export function SelectInput(props: Props): JSX.Element {
+  const { t } = useTranslation();
   const state = useSelectState(props);
 
   const ref = useRef();
@@ -56,7 +58,7 @@ export function SelectInput(props: Props): JSX.Element {
         <span {...valueProps} className={styles.selectedItem}>
           {state.selectedItem
             ? state.selectedItem.rendered
-            : "Select an option"}
+            : t("Select an option")}
         </span>
         <ArrowDownIcon />
       </button>

src/main.tsx

@@ -25,10 +25,15 @@ import ReactDOM from "react-dom";
 import { createBrowserHistory } from "history";
 import * as Sentry from "@sentry/react";
 import { Integrations } from "@sentry/tracing";
+import i18n from "i18next";
+import { initReactI18next } from "react-i18next";
+import Backend from "i18next-http-backend";
+import LanguageDetector from "i18next-browser-languagedetector";
 
 import "./index.css";
 import App from "./App";
 import { init as initRageshake } from "./settings/rageshake";
+import { getUrlParams } from "./UrlParams";
 
 initRageshake();
 
@@ -104,6 +109,35 @@ Sentry.init({
   tracesSampleRate: 1.0,
 });
 
+const languageDetector = new LanguageDetector();
+languageDetector.addDetector({
+  name: "urlFragment",
+  // Look for a language code in the URL's fragment
+  lookup: () => getUrlParams().lang ?? undefined,
+});
+
+i18n
+  .use(Backend)
+  .use(languageDetector)
+  .use(initReactI18next)
+  .init({
+    fallbackLng: "en-GB",
+    defaultNS: "app",
+    keySeparator: false,
+    nsSeparator: false,
+    pluralSeparator: "|",
+    contextSeparator: "|",
+    interpolation: {
+      escapeValue: false, // React has built-in XSS protections
+    },
+    detection: {
+      // No localStorage detectors or caching here, since we don't have any way
+      // of letting the user manually select a language
+      order: ["urlFragment", "navigator"],
+      caches: [],
+    },
+  });
+
 ReactDOM.render(
   <React.StrictMode>
     <App history={history} />

src/matrix-utils.ts

@@ -19,7 +19,7 @@ import {
 import type { MatrixClient } from "matrix-js-sdk/src/client";
 import type { Room } from "matrix-js-sdk/src/models/room";
 import IndexedDBWorker from "./IndexedDBWorker?worker";
-import { getRoomParams } from "./room/useRoomParams";
+import { getUrlParams } from "./UrlParams";
 
 export const defaultHomeserver =
   (import.meta.env.VITE_DEFAULT_HOMESERVER as string) ??
@@ -134,12 +134,12 @@ export async function initClient(
     storeOpts.cryptoStore = new MemoryCryptoStore();
   }
 
-  // XXX: we read from the room params in RoomPage too:
+  // XXX: we read from the URL params in RoomPage too:
   // it would be much better to read them in one place and pass
   // the values around, but we initialise the matrix client in
   // many different places so we'd have to pass it into all of
   // them.
-  const { e2eEnabled } = getRoomParams();
+  const { e2eEnabled } = getUrlParams();
   if (!e2eEnabled) {
     logger.info("Disabling E2E: group call signalling will NOT be encrypted.");
   }

src/profile/ProfileModal.tsx

@@ -16,6 +16,7 @@ limitations under the License.
 
 import React, { ChangeEvent, useCallback, useEffect, useState } from "react";
 import { MatrixClient } from "matrix-js-sdk/src/client";
+import { useTranslation } from "react-i18next";
 
 import { Button } from "../button";
 import { useProfile } from "./useProfile";
@@ -31,6 +32,7 @@ interface Props {
 }
 export function ProfileModal({ client, ...rest }: Props) {
   const { onClose } = rest;
+  const { t } = useTranslation();
   const {
     success,
     error,
@@ -83,14 +85,14 @@ export function ProfileModal({ client, ...rest }: Props) {
   }, [success, onClose]);
 
   return (
-    <Modal title="Profile" isDismissable {...rest}>
+    <Modal title={t("Profile")} isDismissable {...rest}>
       <ModalContent>
         <form onSubmit={onSubmit}>
           <FieldRow className={styles.avatarFieldRow}>
             <AvatarInputField
               id="avatar"
               name="avatar"
-              label="Avatar"
+              label={t("Avatar")}
               avatarUrl={avatarUrl}
               displayName={displayName}
               onRemoveAvatar={onRemoveAvatar}
@@ -100,7 +102,7 @@ export function ProfileModal({ client, ...rest }: Props) {
             <InputField
               id="userId"
               name="userId"
-              label="User Id"
+              label={t("User ID")}
               type="text"
               disabled
               value={client.getUserId()}
@@ -110,18 +112,18 @@ export function ProfileModal({ client, ...rest }: Props) {
             <InputField
               id="displayName"
               name="displayName"
-              label="Display Name"
+              label={t("Display name")}
               type="text"
               required
               autoComplete="off"
-              placeholder="Display Name"
+              placeholder={t("Display name")}
               value={displayName}
               onChange={onChangeDisplayName}
             />
           </FieldRow>
           {error && (
             <FieldRow>
-              <ErrorMessage>{error.message}</ErrorMessage>
+              <ErrorMessage error={error} />
             </FieldRow>
           )}
           <FieldRow rightAlign>
@@ -129,7 +131,7 @@ export function ProfileModal({ client, ...rest }: Props) {
               Cancel
             </Button>
             <Button type="submit" disabled={loading}>
-              {loading ? "Saving..." : "Save"}
+              {loading ? t("Saving…") : t("Save")}
             </Button>
           </FieldRow>
         </form>

src/room/AudioPreview.tsx

@@ -17,6 +17,7 @@ limitations under the License.
 import React from "react";
 import { GroupCallState } from "matrix-js-sdk/src/webrtc/groupCall";
 import { Item } from "@react-stately/collections";
+import { useTranslation } from "react-i18next";
 
 import styles from "./AudioPreview.module.css";
 import { SelectInput } from "../input/SelectInput";
@@ -43,24 +44,26 @@ export function AudioPreview({
   audioOutputs,
   setAudioOutput,
 }: Props) {
+  const { t } = useTranslation();
+
   return (
     <>
-      <h1>{`${roomName} - Walkie-talkie call`}</h1>
+      <h1>{t("{{roomName}} - Walkie-talkie call", { roomName })}</h1>
       <div className={styles.preview}>
         {state === GroupCallState.LocalCallFeedUninitialized && (
           <Body fontWeight="semiBold" className={styles.microphonePermissions}>
-            Microphone permissions needed to join the call.
+            {t("Microphone permissions needed to join the call.")}
           </Body>
         )}
         {state === GroupCallState.InitializingLocalCallFeed && (
           <Body fontWeight="semiBold" className={styles.microphonePermissions}>
-            Accept microphone permissions to join the call.
+            {t("Accept microphone permissions to join the call.")}
           </Body>
         )}
         {state === GroupCallState.LocalCallFeedInitialized && (
           <>
             <SelectInput
-              label="Microphone"
+              label={t("Microphone")}
               selectedKey={audioInput}
               onSelectionChange={setAudioInput}
               className={styles.inputField}
@@ -69,13 +72,13 @@ export function AudioPreview({
                 <Item key={deviceId}>
                   {!!label && label.trim().length > 0
                     ? label
-                    : `Microphone ${index + 1}`}
+                    : t("Microphone {{n}}", { n: index + 1 })}
                 </Item>
               ))}
             </SelectInput>
             {audioOutputs.length > 0 && (
               <SelectInput
-                label="Speaker"
+                label={t("Speaker")}
                 selectedKey={audioOutput}
                 onSelectionChange={setAudioOutput}
                 className={styles.inputField}
@@ -84,7 +87,7 @@ export function AudioPreview({
                   <Item key={deviceId}>
                     {!!label && label.trim().length > 0
                       ? label
-                      : `Speaker ${index + 1}`}
+                      : t("Speaker {{n}}", { n: index + 1 })}
                   </Item>
                 ))}
               </SelectInput>

src/room/CallEndedView.tsx

@@ -16,6 +16,7 @@ limitations under the License.
 
 import React from "react";
 import { MatrixClient } from "matrix-js-sdk/src/client";
+import { Trans, useTranslation } from "react-i18next";
 
 import styles from "./CallEndedView.module.css";
 import { LinkButton } from "../button";
@@ -24,6 +25,7 @@ import { Subtitle, Body, Link, Headline } from "../typography/Typography";
 import { Header, HeaderLogo, LeftNav, RightNav } from "../Header";
 
 export function CallEndedView({ client }: { client: MatrixClient }) {
+  const { t } = useTranslation();
   const { displayName } = useProfile(client);
 
   return (
@@ -37,9 +39,10 @@ export function CallEndedView({ client }: { client: MatrixClient }) {
       <div className={styles.container}>
         <main className={styles.main}>
           <Headline className={styles.headline}>
-            {displayName}, your call is now ended
+            {t("{{displayName}}, your call is now ended", { displayName })}
           </Headline>
           <div className={styles.callEndedContent}>
+            <Trans>
               <Subtitle>
                 Why not finish by setting up a password to keep your account?
               </Subtitle>
@@ -47,19 +50,20 @@ export function CallEndedView({ client }: { client: MatrixClient }) {
                 You'll be able to keep your name and set an avatar for use on
                 future calls
               </Subtitle>
+            </Trans>
             <LinkButton
               className={styles.callEndedButton}
               size="lg"
               variant="default"
               to="/register"
             >
-              Create account
+              {t("Create account")}
             </LinkButton>
           </div>
         </main>
         <Body className={styles.footer}>
           <Link color="primary" to="/">
-            Not now, return to home screen
+            {t("Not now, return to home screen")}
           </Link>
         </Body>
       </div>

src/room/FeedbackModal.tsx

@@ -16,6 +16,7 @@ limitations under the License.
 
 import React, { useCallback, useEffect } from "react";
 import { randomString } from "matrix-js-sdk/src/randomstring";
+import { useTranslation } from "react-i18next";
 
 import { Modal, ModalContent } from "../Modal";
 import { Button } from "../button";
@@ -25,6 +26,7 @@ import {
   useRageshakeRequest,
 } from "../settings/submit-rageshake";
 import { Body } from "../typography/Typography";
+
 interface Props {
   inCall: boolean;
   roomId: string;
@@ -32,7 +34,9 @@ interface Props {
   // TODO: add all props for for <Modal>
   [index: string]: unknown;
 }
+
 export function FeedbackModal({ inCall, roomId, onClose, ...rest }: Props) {
+  const { t } = useTranslation();
   const { submitRageshake, sending, sent, error } = useSubmitRageshake();
   const sendRageshakeRequest = useRageshakeRequest();
 
@@ -67,15 +71,20 @@ export function FeedbackModal({ inCall, roomId, onClose, ...rest }: Props) {
   }, [sent, onClose]);
 
   return (
-    <Modal title="Submit Feedback" isDismissable onClose={onClose} {...rest}>
+    <Modal
+      title={t("Submit feedback")}
+      isDismissable
+      onClose={onClose}
+      {...rest}
+    >
       <ModalContent>
-        <Body>Having trouble? Help us fix it.</Body>
+        <Body>{t("Having trouble? Help us fix it.")}</Body>
         <form onSubmit={onSubmitFeedback}>
           <FieldRow>
             <InputField
               id="description"
               name="description"
-              label="Description (optional)"
+              label={t("Description (optional)")}
               type="textarea"
             />
           </FieldRow>
@@ -83,19 +92,19 @@ export function FeedbackModal({ inCall, roomId, onClose, ...rest }: Props) {
             <InputField
               id="sendLogs"
               name="sendLogs"
-              label="Include Debug Logs"
+              label={t("Include debug logs")}
               type="checkbox"
               defaultChecked
             />
           </FieldRow>
           {error && (
             <FieldRow>
-              <ErrorMessage>{error.message}</ErrorMessage>
+              <ErrorMessage error={error} />
             </FieldRow>
           )}
           <FieldRow>
             <Button type="submit" disabled={sending}>
-              {sending ? "Submitting feedback..." : "Submit Feedback"}
+              {sending ? t("Submitting feedback…") : t("Submit feedback")}
             </Button>
           </FieldRow>
         </form>

src/room/GridLayoutMenu.tsx

@@ -14,8 +14,9 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import React from "react";
+import React, { useCallback } from "react";
 import { Item } from "@react-stately/collections";
+import { useTranslation } from "react-i18next";
 
 import { Button } from "../button";
 import { PopoverMenuTrigger } from "../popover/PopoverMenu";
@@ -27,28 +28,33 @@ import { Menu } from "../Menu";
 import { TooltipTrigger } from "../Tooltip";
 
 export type Layout = "freedom" | "spotlight";
+
 interface Props {
   layout: Layout;
   setLayout: (layout: Layout) => void;
 }
+
 export function GridLayoutMenu({ layout, setLayout }: Props) {
+  const { t } = useTranslation();
+  const tooltip = useCallback(() => t("Change layout"), [t]);
+
   return (
     <PopoverMenuTrigger placement="bottom right">
-      <TooltipTrigger tooltip={() => "Layout Type"}>
+      <TooltipTrigger tooltip={tooltip}>
         <Button variant="icon">
           {layout === "spotlight" ? <SpotlightIcon /> : <FreedomIcon />}
         </Button>
       </TooltipTrigger>
       {(props: JSX.IntrinsicAttributes) => (
-        <Menu {...props} label="Grid layout menu" onAction={setLayout}>
+        <Menu {...props} label={t("Grid layout menu")} onAction={setLayout}>
-          <Item key="freedom" textValue="Freedom">
+          <Item key="freedom" textValue={t("Freedom")}>
             <FreedomIcon />
             <span>Freedom</span>
             {layout === "freedom" && (
               <CheckIcon className={menuStyles.checkIcon} />
             )}
           </Item>
-          <Item key="spotlight" textValue="Spotlight">
+          <Item key="spotlight" textValue={t("Spotlight")}>
             <SpotlightIcon />
             <span>Spotlight</span>
             {layout === "spotlight" && (

src/room/GroupCallLoader.tsx

@@ -17,6 +17,7 @@ limitations under the License.
 import React, { ReactNode } from "react";
 import { MatrixClient } from "matrix-js-sdk/src/client";
 import { GroupCall } from "matrix-js-sdk/src/webrtc/groupCall";
+import { useTranslation } from "react-i18next";
 
 import { useLoadGroupCall } from "./useLoadGroupCall";
 import { ErrorView, FullScreenView } from "../FullScreenView";
@@ -37,6 +38,7 @@ export function GroupCallLoader({
   children,
   createPtt,
 }: Props): JSX.Element {
+  const { t } = useTranslation();
   const { loading, error, groupCall } = useLoadGroupCall(
     client,
     roomIdOrAlias,
@@ -44,12 +46,12 @@ export function GroupCallLoader({
     createPtt
   );
 
-  usePageTitle(groupCall ? groupCall.room.name : "Loading...");
+  usePageTitle(groupCall ? groupCall.room.name : t("Loading…"));
 
   if (loading) {
     return (
       <FullScreenView>
-        <h1>Loading room...</h1>
+        <h1>{t("Loading room…")}</h1>
       </FullScreenView>
     );
   }

src/room/GroupCallView.tsx

@@ -19,6 +19,7 @@ import { useHistory } from "react-router-dom";
 import { GroupCall, GroupCallState } from "matrix-js-sdk/src/webrtc/groupCall";
 import { MatrixClient } from "matrix-js-sdk/src/client";
 import { logger } from "matrix-js-sdk/src/logger";
+import { useTranslation } from "react-i18next";
 
 import type { IWidgetApiRequest } from "matrix-widget-api";
 import { widget, ElementWidgetActions, JoinCallData } from "../widget";
@@ -81,8 +82,8 @@ export function GroupCallView({
     unencryptedEventsFromUsers,
   } = useGroupCall(groupCall);
 
+  const { t } = useTranslation();
   const { setAudioInput, setVideoInput } = useMediaHandler();
-
   const avatarUrl = useRoomAvatar(groupCall.room);
 
   useEffect(() => {
@@ -240,7 +241,7 @@ export function GroupCallView({
   } else if (state === GroupCallState.Entering) {
     return (
       <FullScreenView>
-        <h1>Entering room...</h1>
+        <h1>{t("Entering room…")}</h1>
       </FullScreenView>
     );
   } else if (left) {
@@ -257,7 +258,7 @@ export function GroupCallView({
   } else if (isEmbedded) {
     return (
       <FullScreenView>
-        <h1>Loading room...</h1>
+        <h1>{t("Loading room…")}</h1>
       </FullScreenView>
     );
   } else {

src/room/InCallView.tsx

@@ -23,6 +23,7 @@ import { RoomMember } from "matrix-js-sdk/src/models/room-member";
 import { GroupCall } from "matrix-js-sdk/src/webrtc/groupCall";
 import { CallFeed } from "matrix-js-sdk/src/webrtc/callFeed";
 import classNames from "classnames";
+import { useTranslation } from "react-i18next";
 
 import type { IWidgetApiRequest } from "matrix-widget-api";
 import styles from "./InCallView.module.css";
@@ -112,6 +113,7 @@ export function InCallView({
   unencryptedEventsFromUsers,
   hideHeader,
 }: Props) {
+  const { t } = useTranslation();
   usePreventScroll();
   const containerRef1 = useRef<HTMLDivElement | null>(null);
   const [containerRef2, bounds] = useMeasure({ polyfill: ResizeObserver });
@@ -247,7 +249,7 @@ export function InCallView({
     if (items.length === 0) {
       return (
         <div className={styles.centerMessage}>
-          <p>Waiting for other participants...</p>
+          <p>{t("Waiting for other participants…")}</p>
         </div>
       );
     }

src/room/InviteModal.tsx

@@ -15,6 +15,7 @@ limitations under the License.
 */
 
 import React, { FC } from "react";
+import { useTranslation } from "react-i18next";
 
 import { Modal, ModalContent, ModalProps } from "../Modal";
 import { CopyButton } from "../button";
@@ -25,19 +26,23 @@ interface Props extends Omit<ModalProps, "title" | "children"> {
   roomIdOrAlias: string;
 }
 
-export const InviteModal: FC<Props> = ({ roomIdOrAlias, ...rest }) => (
+export const InviteModal: FC<Props> = ({ roomIdOrAlias, ...rest }) => {
+  const { t } = useTranslation();
+
+  return (
     <Modal
-    title="Invite People"
+      title={t("Invite people")}
       isDismissable
       className={styles.inviteModal}
       {...rest}
     >
       <ModalContent>
-      <p>Copy and share this meeting link</p>
+        <p>{t("Copy and share this call link")}</p>
         <CopyButton
           className={styles.copyButton}
           value={getRoomUrl(roomIdOrAlias)}
         />
       </ModalContent>
     </Modal>
-);
+  );
+};

src/room/LobbyView.tsx

@@ -19,6 +19,7 @@ import { GroupCall, GroupCallState } from "matrix-js-sdk/src/webrtc/groupCall";
 import { MatrixClient } from "matrix-js-sdk/src/client";
 import { PressEvent } from "@react-types/shared";
 import { CallFeed } from "matrix-js-sdk/src/webrtc/callFeed";
+import { useTranslation } from "react-i18next";
 
 import styles from "./LobbyView.module.css";
 import { Button, CopyButton } from "../button";
@@ -66,6 +67,7 @@ export function LobbyView({
   isEmbedded,
   hideHeader,
 }: Props) {
+  const { t } = useTranslation();
   const { stream } = useCallFeed(localCallFeed);
   const {
     audioInput,
@@ -142,15 +144,15 @@ export function LobbyView({
             variant="secondaryCopy"
             value={getRoomUrl(roomIdOrAlias)}
             className={styles.copyButton}
-            copiedMessage="Call link copied"
+            copiedMessage={t("Call link copied")}
           >
-            Copy call link and join later
+            {t("Copy call link and join later")}
           </CopyButton>
         </div>
         {!isEmbedded && (
           <Body className={styles.joinRoomFooter}>
             <Link color="primary" to="/">
-              Take me Home
+              {t("Take me Home")}
             </Link>
           </Body>
         )}

src/room/OverflowMenu.tsx

@@ -18,6 +18,7 @@ import React, { useCallback } from "react";
 import { Item } from "@react-stately/collections";
 import { GroupCall } from "matrix-js-sdk/src/webrtc/groupCall";
 import { OverlayTriggerState } from "@react-stately/overlays";
+import { useTranslation } from "react-i18next";
 
 import { Button } from "../button";
 import { Menu } from "../Menu";
@@ -31,6 +32,7 @@ import { SettingsModal } from "../settings/SettingsModal";
 import { InviteModal } from "./InviteModal";
 import { TooltipTrigger } from "../Tooltip";
 import { FeedbackModal } from "./FeedbackModal";
+
 interface Props {
   roomIdOrAlias: string;
   inCall: boolean;
@@ -42,6 +44,7 @@ interface Props {
     onClose: () => void;
   };
 }
+
 export function OverflowMenu({
   roomIdOrAlias,
   inCall,
@@ -50,6 +53,8 @@ export function OverflowMenu({
   feedbackModalState,
   feedbackModalProps,
 }: Props) {
+  const { t } = useTranslation();
+
   const {
     modalState: inviteModalState,
     modalProps: inviteModalProps,
@@ -90,29 +95,31 @@ export function OverflowMenu({
     [feedbackModalState, inviteModalState, settingsModalState]
   );
 
+  const tooltip = useCallback(() => t("More"), [t]);
+
   return (
     <>
       <PopoverMenuTrigger disableOnState>
-        <TooltipTrigger tooltip={() => "More"} placement="top">
+        <TooltipTrigger tooltip={tooltip} placement="top">
           <Button variant="toolbar">
             <OverflowIcon />
           </Button>
         </TooltipTrigger>
         {(props: JSX.IntrinsicAttributes) => (
-          <Menu {...props} label="more menu" onAction={onAction}>
+          <Menu {...props} label={t("More menu")} onAction={onAction}>
             {showInvite && (
-              <Item key="invite" textValue="Invite people">
+              <Item key="invite" textValue={t("Invite people")}>
                 <AddUserIcon />
-                <span>Invite people</span>
+                <span>{t("Invite people")}</span>
               </Item>
             )}
-            <Item key="settings" textValue="Settings">
+            <Item key="settings" textValue={t("Settings")}>
               <SettingsIcon />
-              <span>Settings</span>
+              <span>{t("Settings")}</span>
             </Item>
-            <Item key="feedback" textValue="Submit Feedback">
+            <Item key="feedback" textValue={t("Submit feedback")}>
               <FeedbackIcon />
-              <span>Submit Feedback</span>
+              <span>{t("Submit feedback")}</span>
             </Item>
           </Menu>
         )}

src/room/PTTCallView.tsx

@@ -17,10 +17,12 @@ limitations under the License.
 import React, { useEffect } from "react";
 import useMeasure from "react-use-measure";
 import { ResizeObserver } from "@juggle/resize-observer";
+import i18n from "i18next";
 import { MatrixClient } from "matrix-js-sdk/src/client";
 import { RoomMember } from "matrix-js-sdk/src/models/room-member";
 import { GroupCall } from "matrix-js-sdk/src/webrtc/groupCall";
 import { CallFeed } from "matrix-js-sdk/src/webrtc/callFeed";
+import { useTranslation } from "react-i18next";
 
 import { useDelayedState } from "../useDelayedState";
 import { useModalTriggerState } from "../Modal";
@@ -50,40 +52,45 @@ function getPromptText(
   talkOverEnabled: boolean,
   activeSpeakerUserId: string,
   activeSpeakerDisplayName: string,
-  connected: boolean
+  connected: boolean,
+  t: typeof i18n.t
 ): string {
-  if (!connected) return "Connection lost";
+  if (!connected) return t("Connection lost");
 
   const isTouchScreen = Boolean(window.ontouchstart !== undefined);
 
   if (networkWaiting) {
-    return "Waiting for network";
+    return t("Waiting for network");
   }
 
   if (showTalkOverError) {
-    return "You can't talk at the same time";
+    return t("You can't talk at the same time");
   }
 
   if (pttButtonHeld && activeSpeakerIsLocalUser) {
     if (isTouchScreen) {
-      return "Release to stop";
+      return t("Release to stop");
     } else {
-      return "Release spacebar key to stop";
+      return t("Release spacebar key to stop");
     }
   }
 
   if (talkOverEnabled && activeSpeakerUserId && !activeSpeakerIsLocalUser) {
     if (isTouchScreen) {
-      return `Press and hold to talk over ${activeSpeakerDisplayName}`;
+      return t("Press and hold to talk over {{name}}", {
+        name: activeSpeakerDisplayName,
+      });
     } else {
-      return `Press and hold spacebar to talk over ${activeSpeakerDisplayName}`;
+      return t("Press and hold spacebar to talk over {{name}}", {
+        name: activeSpeakerDisplayName,
+      });
     }
   }
 
   if (isTouchScreen) {
-    return "Press and hold to talk";
+    return t("Press and hold to talk");
   } else {
-    return "Press and hold spacebar to talk";
+    return t("Press and hold spacebar to talk");
   }
 }
 
@@ -112,6 +119,7 @@ export const PTTCallView: React.FC<Props> = ({
   isEmbedded,
   hideHeader,
 }) => {
+  const { t } = useTranslation();
   const { modalState: inviteModalState, modalProps: inviteModalProps } =
     useModalTriggerState();
   const { modalState: feedbackModalState, modalProps: feedbackModalProps } =
@@ -195,9 +203,11 @@ export const PTTCallView: React.FC<Props> = ({
         {showControls && (
           <>
             <div className={styles.participants}>
-              <p>{`${participants.length} ${
+              <p>
-                participants.length > 1 ? "people" : "person"
+                {t("{{count}} people connected", {
-              } connected`}</p>
+                  count: participants.length,
+                })}
+              </p>
               <Facepile
                 size={facepileSize}
                 max={8}
@@ -230,8 +240,10 @@ export const PTTCallView: React.FC<Props> = ({
                     <AudioIcon className={styles.speakerIcon} />
                   )}
                   {activeSpeakerIsLocalUser
-                    ? "Talking..."
+                    ? t("Talking…")
-                    : `${activeSpeakerDisplayName} is talking...`}
+                    : t("{{name}} is talking…", {
+                        name: activeSpeakerDisplayName,
+                      })}
                 </h2>
                 <Timer value={activeSpeakerUserId} />
               </div>
@@ -263,7 +275,8 @@ export const PTTCallView: React.FC<Props> = ({
                 talkOverEnabled,
                 activeSpeakerUserId,
                 activeSpeakerDisplayName,
-                connected
+                connected,
+                t
               )}
             </p>
           )}
@@ -278,7 +291,7 @@ export const PTTCallView: React.FC<Props> = ({
             <Toggle
               isSelected={talkOverEnabled}
               onChange={setTalkOverEnabled}
-              label="Talk over speaker"
+              label={t("Talk over speaker")}
               id="talkOverEnabled"
             />
           )}

src/room/RageshakeRequestModal.tsx

@@ -15,6 +15,7 @@ limitations under the License.
 */
 
 import React, { FC, useEffect } from "react";
+import { useTranslation } from "react-i18next";
 
 import { Modal, ModalContent, ModalProps } from "../Modal";
 import { Button } from "../button";
@@ -33,6 +34,7 @@ export const RageshakeRequestModal: FC<Props> = ({
   roomIdOrAlias,
   ...rest
 }) => {
+  const { t } = useTranslation();
   const { submitRageshake, sending, sent, error } = useSubmitRageshake();
 
   useEffect(() => {
@@ -42,11 +44,12 @@ export const RageshakeRequestModal: FC<Props> = ({
   }, [sent, rest]);
 
   return (
-    <Modal title="Debug Log Request" isDismissable {...rest}>
+    <Modal title={t("Debug log request")} isDismissable {...rest}>
       <ModalContent>
         <Body>
-          Another user on this call is having an issue. In order to better
+          {t(
-          diagnose these issues we'd like to collect a debug log.
+            "Another user on this call is having an issue. In order to better diagnose these issues we'd like to collect a debug log."
+          )}
         </Body>
         <FieldRow>
           <Button
@@ -59,12 +62,12 @@ export const RageshakeRequestModal: FC<Props> = ({
             }
             disabled={sending}
           >
-            {sending ? "Sending debug log..." : "Send debug log"}
+            {sending ? t("Sending debug log…") : t("Send debug log")}
           </Button>
         </FieldRow>
         {error && (
           <FieldRow>
-            <ErrorMessage>{error.message}</ErrorMessage>
+            <ErrorMessage error={error} />
           </FieldRow>
         )}
       </ModalContent>

src/room/RoomAuthView.tsx

@@ -16,6 +16,7 @@ limitations under the License.
 
 import React, { useCallback, useState } from "react";
 import { useLocation } from "react-router-dom";
+import { Trans, useTranslation } from "react-i18next";
 
 import styles from "./RoomAuthView.module.css";
 import { Button } from "../button";
@@ -50,6 +51,7 @@ export function RoomAuthView() {
     [registerPasswordlessUser]
   );
 
+  const { t } = useTranslation();
   const location = useLocation();
 
   return (
@@ -64,35 +66,38 @@ export function RoomAuthView() {
       </Header>
       <div className={styles.container}>
         <main className={styles.main}>
-          <Headline className={styles.headline}>Join Call</Headline>
+          <Headline className={styles.headline}>{t("Join call")}</Headline>
           <Form className={styles.form} onSubmit={onSubmit}>
             <FieldRow>
               <InputField
                 id="displayName"
                 name="displayName"
-                label="Display Name"
+                label={t("Display name")}
-                placeholder="Display Name"
+                placeholder={t("Display name")}
                 type="text"
                 required
                 autoComplete="off"
               />
             </FieldRow>
             <Caption>
+              <Trans>
                 By clicking "Join call now", you agree to our{" "}
                 <Link href={privacyPolicyUrl}>Terms and conditions</Link>
+              </Trans>
             </Caption>
             {error && (
               <FieldRow>
-                <ErrorMessage>{error.message}</ErrorMessage>
+                <ErrorMessage error={error} />
               </FieldRow>
             )}
             <Button type="submit" size="lg" disabled={loading}>
-              {loading ? "Loading..." : "Join call now"}
+              {loading ? t("Loading…") : t("Join call now")}
             </Button>
             <div id={recaptchaId} />
           </Form>
         </main>
         <Body className={styles.footer}>
+          <Trans>
             {"Not registered yet? "}
             <Link
               color="primary"
@@ -100,6 +105,7 @@ export function RoomAuthView() {
             >
               Create an account
             </Link>
+          </Trans>
         </Body>
       </div>
     </>

src/room/RoomPage.tsx

@@ -15,6 +15,7 @@ limitations under the License.
 */
 
 import React, { FC, useEffect, useState, useCallback } from "react";
+import { useTranslation } from "react-i18next";
 
 import type { GroupCall } from "matrix-js-sdk/src/webrtc/groupCall";
 import { useClient } from "../ClientContext";
@@ -22,11 +23,13 @@ import { ErrorView, LoadingView } from "../FullScreenView";
 import { RoomAuthView } from "./RoomAuthView";
 import { GroupCallLoader } from "./GroupCallLoader";
 import { GroupCallView } from "./GroupCallView";
-import { useRoomParams } from "./useRoomParams";
+import { useUrlParams } from "../UrlParams";
 import { MediaHandlerProvider } from "../settings/useMediaHandler";
 import { useRegisterPasswordlessUser } from "../auth/useRegisterPasswordlessUser";
+import { translatedError } from "../TranslatedError";
 
 export const RoomPage: FC = () => {
+  const { t } = useTranslation();
   const { loading, isAuthenticated, error, client, isPasswordlessUser } =
     useClient();
 
@@ -39,9 +42,9 @@ export const RoomPage: FC = () => {
     hideHeader,
     isPtt,
     displayName,
-  } = useRoomParams();
+  } = useUrlParams();
   const roomIdOrAlias = roomId ?? roomAlias;
-  if (!roomIdOrAlias) throw new Error("No room specified");
+  if (!roomIdOrAlias) throw translatedError("No room specified", t);
 
   const { registerPasswordlessUser } = useRegisterPasswordlessUser();
   const [isRegistering, setIsRegistering] = useState(false);

src/room/VideoPreview.tsx

@@ -19,6 +19,7 @@ import useMeasure from "react-use-measure";
 import { ResizeObserver } from "@juggle/resize-observer";
 import { GroupCallState } from "matrix-js-sdk/src/webrtc/groupCall";
 import { MatrixClient } from "matrix-js-sdk/src/client";
+import { useTranslation } from "react-i18next";
 
 import { MicButton, VideoButton } from "../button";
 import { useMediaStream } from "../video-grid/useMediaStream";
@@ -40,6 +41,7 @@ interface Props {
   audioOutput: string;
   stream: MediaStream;
 }
+
 export function VideoPreview({
   client,
   state,
@@ -51,6 +53,7 @@ export function VideoPreview({
   audioOutput,
   stream,
 }: Props) {
+  const { t } = useTranslation();
   const videoRef = useMediaStream(stream, audioOutput, true);
   const { displayName, avatarUrl } = useProfile(client);
   const [previewRef, previewBounds] = useMeasure({ polyfill: ResizeObserver });
@@ -64,12 +67,12 @@ export function VideoPreview({
       <video ref={videoRef} muted playsInline disablePictureInPicture />
       {state === GroupCallState.LocalCallFeedUninitialized && (
         <Body fontWeight="semiBold" className={styles.cameraPermissions}>
-          Camera/microphone permissions needed to join the call.
+          {t("Camera/microphone permissions needed to join the call.")}
         </Body>
       )}
       {state === GroupCallState.InitializingLocalCallFeed && (
         <Body fontWeight="semiBold" className={styles.cameraPermissions}>
-          Accept camera/microphone permissions to join the call.
+          {t("Accept camera/microphone permissions to join the call.")}
         </Body>
       )}
       {state === GroupCallState.LocalCallFeedInitialized && (

src/room/useGroupCall.ts

@@ -26,8 +26,10 @@ import {
 import { MatrixCall } from "matrix-js-sdk/src/webrtc/call";
 import { CallFeed } from "matrix-js-sdk/src/webrtc/callFeed";
 import { RoomMember } from "matrix-js-sdk/src/models/room-member";
+import { useTranslation } from "react-i18next";
 
 import { usePageUnload } from "./usePageUnload";
+import { TranslatedError, translatedError } from "../TranslatedError";
 
 export interface UseGroupCallReturnType {
   state: GroupCallState;
@@ -37,7 +39,7 @@ export interface UseGroupCallReturnType {
   userMediaFeeds: CallFeed[];
   microphoneMuted: boolean;
   localVideoMuted: boolean;
-  error: Error;
+  error: TranslatedError | null;
   initLocalCallFeed: () => void;
   enter: () => void;
   leave: () => void;
@@ -60,7 +62,7 @@ interface State {
   localCallFeed: CallFeed;
   activeSpeaker: string;
   userMediaFeeds: CallFeed[];
-  error: Error;
+  error: TranslatedError | null;
   microphoneMuted: boolean;
   localVideoMuted: boolean;
   screenshareFeeds: CallFeed[];
@@ -309,15 +311,18 @@ export function useGroupCall(groupCall: GroupCall): UseGroupCallReturnType {
       });
   }, [groupCall]);
 
+  const { t } = useTranslation();
+
   useEffect(() => {
     if (window.RTCPeerConnection === undefined) {
-      const error = new Error(
+      const error = translatedError(
-        "WebRTC is not supported or is being blocked in this browser."
+        "WebRTC is not supported or is being blocked in this browser.",
+        t
       );
       console.error(error);
       updateState({ error });
     }
-  }, []);
+  }, [t]);
 
   return {
     state,

src/room/useLoadGroupCall.ts

@@ -24,10 +24,12 @@ import { GroupCallEventHandlerEvent } from "matrix-js-sdk/src/webrtc/groupCallEv
 import { logger } from "matrix-js-sdk/src/logger";
 import { ClientEvent, MatrixClient } from "matrix-js-sdk/src/client";
 import { SyncState } from "matrix-js-sdk/src/sync";
+import { useTranslation } from "react-i18next";
 
 import type { Room } from "matrix-js-sdk/src/models/room";
 import type { GroupCall } from "matrix-js-sdk/src/webrtc/groupCall";
 import { isLocalRoomId, createRoom, roomNameFromRoomId } from "../matrix-utils";
+import { translatedError } from "../TranslatedError";
 
 export interface GroupCallLoadState {
   loading: boolean;
@@ -41,6 +43,7 @@ export const useLoadGroupCall = (
   viaServers: string[],
   createPtt: boolean
 ): GroupCallLoadState => {
+  const { t } = useTranslation();
   const [state, setState] = useState<GroupCallLoadState>({ loading: true });
 
   useEffect(() => {
@@ -122,7 +125,7 @@ export const useLoadGroupCall = (
 
         const timeout = setTimeout(() => {
           client.off(GroupCallEventHandlerEvent.Incoming, onGroupCallIncoming);
-          reject(new Error("Fetching group call timed out."));
+          reject(translatedError("Fetching group call timed out.", t));
         }, 30000);
       });
     };
@@ -153,7 +156,7 @@ export const useLoadGroupCall = (
       .catch((error) =>
         setState((prevState) => ({ ...prevState, loading: false, error }))
       );
-  }, [client, roomIdOrAlias, viaServers, createPtt]);
+  }, [client, roomIdOrAlias, viaServers, createPtt, t]);
 
   return state;
 };

src/settings/SettingsModal.tsx

@@ -16,6 +16,7 @@ limitations under the License.
 
 import React from "react";
 import { Item } from "@react-stately/collections";
+import { useTranslation } from "react-i18next";
 
 import { Modal } from "../Modal";
 import styles from "./SettingsModal.module.css";
@@ -37,6 +38,7 @@ interface Props {
 }
 
 export const SettingsModal = (props: Props) => {
+  const { t } = useTranslation();
   const {
     audioInput,
     audioInputs,
@@ -56,7 +58,7 @@ export const SettingsModal = (props: Props) => {
 
   return (
     <Modal
-      title="Settings"
+      title={t("Settings")}
       isDismissable
       mobileFullScreen
       className={styles.settingsModal}
@@ -67,12 +69,12 @@ export const SettingsModal = (props: Props) => {
           title={
             <>
               <AudioIcon width={16} height={16} />
-              <span>Audio</span>
+              <span>{t("Audio")}</span>
             </>
           }
         >
           <SelectInput
-            label="Microphone"
+            label={t("Microphone")}
             selectedKey={audioInput}
             onSelectionChange={setAudioInput}
           >
@@ -80,13 +82,13 @@ export const SettingsModal = (props: Props) => {
               <Item key={deviceId}>
                 {!!label && label.trim().length > 0
                   ? label
-                  : `Microphone ${index + 1}`}
+                  : t("Microphone {{n}}", { n: index + 1 })}
               </Item>
             ))}
           </SelectInput>
           {audioOutputs.length > 0 && (
             <SelectInput
-              label="Speaker"
+              label={t("Speaker")}
               selectedKey={audioOutput}
               onSelectionChange={setAudioOutput}
             >
@@ -94,7 +96,7 @@ export const SettingsModal = (props: Props) => {
                 <Item key={deviceId}>
                   {!!label && label.trim().length > 0
                     ? label
-                    : `Speaker ${index + 1}`}
+                    : t("Speaker {{n}}", { n: index + 1 })}
                 </Item>
               ))}
             </SelectInput>
@@ -102,10 +104,12 @@ export const SettingsModal = (props: Props) => {
           <FieldRow>
             <InputField
               id="spatialAudio"
-              label="Spatial audio"
+              label={t("Spatial audio")}
               type="checkbox"
               checked={spatialAudio}
-              description="This will make a speaker's audio seem as if it is coming from where their tile is positioned on screen. (Experimental feature: this may impact the stability of audio.)"
+              description={t(
+                "This will make a speaker's audio seem as if it is coming from where their tile is positioned on screen. (Experimental feature: this may impact the stability of audio.)"
+              )}
               onChange={(event: React.ChangeEvent<HTMLInputElement>) =>
                 setSpatialAudio(event.target.checked)
               }
@@ -116,12 +120,12 @@ export const SettingsModal = (props: Props) => {
           title={
             <>
               <VideoIcon width={16} height={16} />
-              <span>Video</span>
+              <span>{t("Video")}</span>
             </>
           }
         >
           <SelectInput
-            label="Camera"
+            label={t("Camera")}
             selectedKey={videoInput}
             onSelectionChange={setVideoInput}
           >
@@ -129,7 +133,7 @@ export const SettingsModal = (props: Props) => {
               <Item key={deviceId}>
                 {!!label && label.trim().length > 0
                   ? label
-                  : `Camera ${index + 1}`}
+                  : t("Camera {{n}}", { n: index + 1 })}
               </Item>
             ))}
           </SelectInput>
@@ -138,20 +142,22 @@ export const SettingsModal = (props: Props) => {
           title={
             <>
               <DeveloperIcon width={16} height={16} />
-              <span>Developer</span>
+              <span>{t("Developer")}</span>
             </>
           }
         >
           <FieldRow>
             <Body className={styles.fieldRowText}>
-              Version: {import.meta.env.VITE_APP_VERSION || "dev"}
+              {t("Version: {{version}}", {
+                version: import.meta.env.VITE_APP_VERSION || "dev",
+              })}
             </Body>
           </FieldRow>
           <FieldRow>
             <InputField
               id="showInspector"
               name="inspector"
-              label="Show Call Inspector"
+              label={t("Show call inspector")}
               type="checkbox"
               checked={showInspector}
               onChange={(e: React.ChangeEvent<HTMLInputElement>) =>
@@ -160,7 +166,9 @@ export const SettingsModal = (props: Props) => {
             />
           </FieldRow>
           <FieldRow>
-            <Button onPress={downloadDebugLog}>Download Debug Logs</Button>
+            <Button onPress={downloadDebugLog}>
+              {t("Download debug logs")}
+            </Button>
           </FieldRow>
         </TabItem>
       </TabContainer>

src/video-grid/VideoTile.tsx

@@ -17,6 +17,7 @@ limitations under the License.
 import React, { forwardRef } from "react";
 import { animated } from "@react-spring/web";
 import classNames from "classnames";
+import { useTranslation } from "react-i18next";
 
 import styles from "./VideoTile.module.css";
 import { ReactComponent as MicMutedIcon } from "../icons/MicMuted.svg";
@@ -66,6 +67,8 @@ export const VideoTile = forwardRef<HTMLDivElement, Props>(
     },
     ref
   ) => {
+    const { t } = useTranslation();
+
     const toolbarButtons: JSX.Element[] = [];
     if (!isLocal) {
       toolbarButtons.push(
@@ -111,7 +114,7 @@ export const VideoTile = forwardRef<HTMLDivElement, Props>(
         {!maximised &&
           (screenshare ? (
             <div className={styles.presenterLabel}>
-              <span>{`${name} is presenting`}</span>
+              <span>{t("{{name}} is presenting", { name })}</span>
             </div>
           ) : (
             <div className={classNames(styles.infoBubble, styles.memberName)}>

src/video-grid/VideoTileSettingsModal.tsx

@@ -16,6 +16,7 @@ limitations under the License.
 
 import React, { ChangeEvent, useState } from "react";
 import { CallFeed } from "matrix-js-sdk/src/webrtc/callFeed";
+import { useTranslation } from "react-i18next";
 
 import { FieldRow } from "../input/Input";
 import { Modal } from "../Modal";
@@ -61,10 +62,12 @@ interface Props {
 }
 
 export const VideoTileSettingsModal = ({ feed, ...rest }: Props) => {
+  const { t } = useTranslation();
+
   return (
     <Modal
       className={styles.videoTileSettingsModal}
-      title="Local volume"
+      title={t("Local volume")}
       isDismissable
       mobileFullScreen
       {...rest}

src/widget.ts

@@ -22,7 +22,7 @@ import { WidgetApi, MatrixCapabilities } from "matrix-widget-api";
 import type { MatrixClient } from "matrix-js-sdk/src/client";
 import type { IWidgetApiRequest } from "matrix-widget-api";
 import { LazyEventEmitter } from "./LazyEventEmitter";
-import { getRoomParams } from "./room/useRoomParams";
+import { getUrlParams } from "./UrlParams";
 
 // Subset of the actions in matrix-react-sdk
 export enum ElementWidgetActions {
@@ -80,7 +80,7 @@ export const widget: WidgetHelpers | null = (() => {
       // We need to do this now rather than later because it has capabilities to
       // request, and is responsible for starting the transport (should it be?)
 
-      const { roomId, userId, deviceId } = getRoomParams();
+      const { roomId, userId, deviceId } = getUrlParams();
       if (!roomId) throw new Error("Room ID must be supplied");
       if (!userId) throw new Error("User ID must be supplied");
       if (!deviceId) throw new Error("Device ID must be supplied");

vite.config.js

@@ -29,7 +29,7 @@ export default defineConfig(({ mode }) => {
     },
     plugins: [
       svgrPlugin(),
-      htmlTemplate({
+      htmlTemplate.default({
         data: {
           title: env.VITE_PRODUCT_NAME || "Matrix Video Chat",
         },