https://github.com/mdn/webextensions-examples

Maintained by the MDN team at Mozilla.

WebExtensions are a way to write browser extensions: that is, programs installed inside a web browser that modify the behaviour of the browser or of web pages loaded by the browser. They are built on a set of cross-browser APIs, so WebExtensions written for Google Chrome or Opera will in most cases run in Firefox or Edge too.

The "webextensions-examples" repository is a collection of simple but complete and installable WebExtensions. You can use the examples to see how to use the WebExtensions APIs, and as a starting point for your own WebExtensions.

The examples are made available under the Mozilla Public License 2.0.

To use the repository, first clone it.

Each example is in its own top-level directory. Install an example in your favourite web browser (installation instructions are below), and see how it works. Each example has its own short README explaining what it does.

To find your way around a WebExtension's internal structure, have a look at the Anatomy of a WebExtension page on MDN.

To use these examples in Firefox, you need at least Firefox 45. Some examples rely on APIs that were added in more recent versions of Firefox. To check the minimum version of Firefox needed for a given example, see the strict_min_version part of the applications key in the example's manifest.json file.

There are a couple ways to try out the example extensions in this repository.

1. Open Firefox and load about:debugging in the URL bar. Click the Load Temporary Add-on button and select the manifest.json file within the directory of an example extension you'd like to install. Here is a video that demonstrates how to do this.
2. Install the web-ext tool, change into the directory of the example extension you'd like to install, and type web-ext run. This will launch Firefox and install the extension automatically. This tool gives you some additional development features such as automatic reloading.

To learn more about developing WebExtensions, see the WebExtensions documentation on MDN for getting started guides, tutorials, and full API reference docs.

If you find a problem, please file a bug.

If you need help, email the dev-addons mailing list or contact the WebExtensions team in the #webextensions IRC channel on irc.mozilla.org.

We welcome contributions, whether they are whole new examples, new features, bug fixes, or translations of localizable strings into new languages. Please see the CONTRIBUTING.md file for more details.