Customize Firefox

Add-ons let millions of Firefox users enhance their browsing experience. If you know HTML, JavaScript, and CSS, you already have all the necessary skills to make a great add-on.

Learn How to Make an Add-on

Port a Chrome Extension

Firefox supports WebExtension APIs, which in most cases are compatible with the extension APIs supported by Chrome, Opera and Edge, so your extensions will run in Firefox with just a few changes.

Learn How

Publish Your Add-on

Have an add-on ready? Submit your extension or theme to be listed on or sign and distribute your extension on your own.

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Help us improve the developer experience

We’re interested in your feedback about the extension development experience! Take our short survey to let us know what kinds of documentation, APIs, and tools would be most useful to your development work.

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