WebIDE

Develop, deploy and debug Firefox OS apps directly in your browser, or on a Firefox OS device, with this tool that replaces App Manager.
Learn more about WebIDE
Valence

Develop and debug your apps across multiple browsers and devices with this powerful extension that comes pre-installed with Firefox Developer Edition.
Learn more about Valence

Important: Sync your new profile

Developer Edition comes with a new profile so you can run it alongside other versions of Firefox. To access your bookmarks, browsing history and more, you need to sync the profile with your existing Firefox Account, or create a new one. Learn more

Page Inspector

Examine the HTML and CSS of any Web page and easily modify the structure and layout of a page.
Learn more about Page Inspector
Web Console

See logged information associated with a Web page and use Web Console to interact with Web pages using JavaScript.
Learn more about Web Console
JavaScript Debugger

Step through JavaScript code and examine or modify its state to help track down bugs.
Learn more about JavaScript Debugger
Network Monitor

See all the network requests your browser makes, how long each request takes and details of each request.
Learn more about Network Monitor
Web Audio Editor

Inspect and interact with Web Audio API in real time to ensure that all audio nodes are connected in the way you expect.
Learn more about Web Audio Editor
Style Editor

View and edit CSS styles associated with a Web page, create new ones and apply existing CSS stylesheets to any page.
Learn more about Style Editor

WebIDE

Valence

Important: Sync your new profile

Page Inspector

Web Console

JavaScript Debugger

Network Monitor

Web Audio Editor

Style Editor