Extend the Web
Get help creating and publishing Firefox add-ons that make browsing smarter, safer, and faster.
You’ll find the resources you need, whether you’re getting started with extension development, preparing to launch your innovation, or developing a custom enterprise solution.
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.
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.
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.
Your extension might already be compatible!
See if your extension works in Firefox. Simply upload your .crx file.
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.
Ask questions in the forum
Connect with other extension developers
Email the community
Latest Developer News
Manifest v3 update
Two years ago, Google proposed Manifest v3, a number of foundational changes to the Chrome extension framework. Many of these changes introduce new incompatibilities between Firefox and Chrome. As we previously wrote, we want to maintain a high degree of …
The post Manifest v3 update appeared first on .
Connect With Us
Extensions Developer Newsletter
Stay up-to-date on news and events for Firefox extension developers.
Portions of this content are ©1998–2021 by individual mozilla.org contributors. Content available under a Creative Commons license