## FAQs

CARTO.js v4 introduces new concepts that in some cases, change the behavior of old components. This section clarifies those changes and describe new functionality.

### Do I need an API Key?

Yes. See the guide _[Get API Key]({{site.cartojs_docs}}/guides/get-api-key/)_ or the [full reference API]({{site.cartojs_docs}}/reference/#authentication) for details.

If you want to learn more about authorization and authentication in the CARTO Platform, read the [fundamentals]({{site.fundamental_docs}}/authorization/) about this topic, or dig into the [Auth API]({{site.authapi_docs}}/) details.

### How do I pay for my API Keys?

All billing is managed through your CARTO account.

The release of the updated CARTO.js library does not impact your plan in any way. There are no changes in terms of costs or payments of your CARTO use.

### What are the main features of this release?

This new library allows you to create custom Location Intelligence applications using Builder capabilities.

Highlights of this release include the ability to:

1. Display data from datasets managed in Builder on a Leaflet map.
2. Manage layers programmatically.
3. Get data from CARTO to create custom UI components using Dataviews.

You can learn more about these main features reading the [final release announcement]({{site.cartojs_docs}}/support/release-announcement/).

### Where's the repository now?

The repo has been renamed and moved to https://github.com/CartoDB/carto.js.

### Does CARTO.js support Named Maps?

No.

Named Maps was a powerful and popular feature yet not easy to understand. Named maps were designed as a workaround for some of the limitations of our API keys. Named maps' purpose might be replicated by the new authorization system.

### Can I still use `cartodb.createVis` and `viz.json` URLs?

No, you cannot.

While `cartodb.createVis` and `viz.json` URLs were convenient and allowed you to prototype a map using CARTO Editor (the former version of Builder) to create a custom app, the functionality of the library has changed.

In CARTO.js v4, we are taking a more programmatic, low-level approach and identifying components that are separate from the front-end tool (CARTO Builder). This will make the API easier to use and more intuitive, giving developers greater flexibility in maintaining their core application.

### Is CartoDB.js v.3.15 still available?

Yes.

Both the [source code](https://github.com/CartoDB/carto.js/tree/v3.15.14) and the [documentation](https://carto.com/docs/carto-engine/carto-js/) are still available.