Add-ons Articles
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Always Right – An Extension Migration Story
A veteran Firefox add-on developer describes how he migrated Always Right, one of his personal must-have browser extensions, to the new WebExtensions API.
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Introducing the Extension Compatibility Tester
With Firefox’s move to a modern web-style browser extension API, it’s now possible to maintain one codebase and ship an extension in multiple browsers. However, since different browsers can have different capabilities, some extensions may require modification to be truly portable. With this in mind, we’ve built the Extension Compatibility Tester.
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Inspect, Modify, and Debug React and Redux in Firefox with Add-ons
React, along with Redux, is one of the fastest and most flexible UI frameworks on the web. It’s easy to write, easy to use and is great for teams. However, it's not easy to debug them in the browser. Now, browser add-ons like React Developer Tools, Redux DevTools, and Vue let you inspect, modify, and debug your code right in the browser.
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Cross-browser extensions, available now in Firefox
We’re modernizing the way developers build extensions for Firefox! We call the new APIs WebExtensions , because they’re written using the technologies of the Web: HTML, CSS, and JavaScript. And just like the technologies of the Web, you can write one codebase that works in multiple places.
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Introducing FilterBubbler: A WebExtension built using React/Redux
We're building a text analysis toolkit with the new WebExtensions API. This toolkit will let you monitor various browser activities and resources (history, bookmarks, etc.) and then let you use text analysis modules to discover patterns in your own browsing history. The idea was to turn the tables on the kinds of sophisticated analysis that advertisers do with the everyday browsing activities we take for granted. We're building this project using React/Redux tooling, and in this post we walk you through some of our design challenges and the decisions we made.
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Firefox 53: Quantum Compositor, Compact Themes, CSS Masks, and More
Firefox 53 includes the first significant piece of Project Quantum, the Quantum Compositor for Windows. Dig in to features and under-the-hood improvements such as compact themes, new WebExtension features, the CSS mask property, and more.
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Building an iOS-style “Unread Notifications” add-on for Firefox OS
What is a Firefox OS add-on and why do we need it? The Firefox add-on ecosystem has been a key differentiator in the desktop browser arena. However, the mobile space lacks a strong add-on framework. Some solutions exist for Android, such as Xposed, but these solutions typically require a rooted phone, and the content is […]
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Porting Chrome Extensions to Firefox with WebExtensions
After reading last month’s “Let’s Write a Web Extension,” I was inspired to try and port a real-world add-on to a WebExtension. Specifically, I tried to port the Chrome version of the popular, open-source “Reddit Enhancement Suite” (RES) to Firefox. Here’s what I learned, and what you can do today to prepare your own add-ons […]
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Let’s Write a Web Extension
You might have heard about Mozilla’s WebExtensions, our implementation of a new browser extension API for writing multiprocess-compatible add-ons. Maybe you’ve been wondering what it was about, and how you could use it. Well, I’m here to help! I think the MDN’s WebExtensions docs are a pretty great place to start: WebExtensions are a new […]
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RDP Inspector: An extension for Firefox Developer Tools
RDP Inspector is a Firefox extension that intercepts the Remote Debugging Protocol (RDP) and allows inspection of all data sent and received. This extension is useful for anyone who wants to extend native developer tools in Firefox by implementing new remotable features or for those who want to learn more about how built-in tools use […]

