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
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.
Manifest.json
Manifest.json
Build extensions
It's easy to create your cross-browser extension for Firefox. Where your development journey begins depends on your skill and experience.
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.
Learn
Develop
Test & Debug
Publish
Manage
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
Your extension might already be compatible!
See if your extension works in Firefox. Simply upload your .crx file to the Developer Hub.
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.