Why Create Extensions on Firefox?
Get your great idea into the hands of millions of Firefox users. Join an international community of developers. Be supported every step of the way. And, when you build for Firefox first, it’s easy to port your extension to other browsers, saving you valuable development time.
Cool Things Add-ons Can Do
Tinker with Tabs
Your extension can control browser tabs. Use the API to open, close, move, hide, and perform other tab management actions.
Learn more about tabs
Integrate Web Search
Use Firefox's powerful built-in search capabilities to open up the web for users from within your own extension.
Learn about enhancing content
Add Innovative Features
Think the browser is missing a feature, such as a built-in calculator, music streaming, or language translation? Add a toolbar button to expose your extension's new capabilities.
Anatomy of an Extension
An extension is a simple collection of files that modify the browser’s appearance and behavior. It can add user interface elements, alter content, or perform background tasks that enhance browsing.
It's easy to create your cross-browser extension for Firefox. Where your development journey begins depends on your skill and experience.
Brand new to extensions development?
MDN web docs will onboard you to the basics. With tutorials from simple user interface changes to complex event handling, MDN covers the structure and API behind extensions. Once you know the fundamentals, come back here to learn how Firefox takes extension development to the next level.
Learn the fundamentals on MDN
Ready to build an extension for Firefox?
If you know the basics of extension development, you’re ready to create an extension for Firefox. We’ve got all the resources you need right here. Learn about cross-browser development. Get tips on testing. Make user updates smooth and painless.
Test & Debug
Build secure extensions
Mozilla takes the safety and privacy of its users very seriously. Be sure to review and follow these practices and policies so you can make your great idea a reality.
Build across browsers
Firefox is at the forefront of cross-browser compatibility. Firefox add-ons are built using the WebExtensions API, so your creation will be accessible to users no matter what browser they use.
Learn about browser differences
Your extension might already be compatible!
See if your extension works in Firefox. Simply upload your
Need some extra help along the way?
When you build on Firefox, you build with a community of add-on developers. And they’re eager to share their expertise and answer your questions.