Leaflet is a modern, lightweight open-source JavaScript library for mobile-friendly interactive maps, developed by Vladimir Agafonkin of CloudMade with a team of dedicated contributors. Weighting just about 25kb of gzipped JS code, it still has all the features most developers ever need for online maps, while providing a fast, pleasant user experience.

It is built from the ground up to work efficiently and smoothly on both desktop and mobile platforms like iOS and Android, taking advantage of HTML5 and CSS3 on modern browsers. The focus is on usability, performance, small size, A-grade browser support, flexibility and easy to use API with convention over configuration. The OOP-based code of the library is designed to be modular, extensible and very easy to understand.

Check out the website for more information: leafletjs.com

Contributing to Leaflet

Let's make the best open-source library for maps that can possibly exist!

Contributing is simple: make the changes in your fork (preferably in a separate branch), make sure that Leaflet builds successfully (see below) and then create a pull request (without the built files, just the source changes) to Vladimir Agafonkin (Leaflet maintainer). Updates to Leaflet documentation and examples (located in the gh-pages branch for current stable release and gh-pages-master for the in-progress version) are really appreciated too.

Note that bugfixes and small improvements are higher priority than new features or substantial API changes, and will be reviewed and merged much faster than pulls with lots of new code. If your new feature is not expected to be widely used, consider making a plugin instead. Lets keep Leaflet slim, fast and simple!

Here's a list of the awesome people that joined us already. Looking forward to your contributions!

Building Leaflet

Leaflet build system is powered by the Node.js platform and Jake, JSHint and UglifyJS libraries, which install easily and work well across all major platforms. Here are the steps to install it:

1. Download and install Node
2. Run the following commands in the command line:

npm install -g jake
npm install jshint
npm install uglify-js

Now that you have everything installed, run jake inside the Leaflet directory. This will check Leaflet source files for JavaScript errors and inconsistencies, and then combine and compress it to the dist folder.

To make a custom build of the library with only the things you need, use the build helper (build/build.html) to choose the components (it figures out dependencies for you) and then run the command generated with it.

If you add any new files to the Leaflet source, make sure to also add them to build/deps.js so that the build system knows about them. Happy coding!