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A browser extension that adds various web developer tools to a browser.
JavaScript CSS

Web Developer

The Web Developer extension adds various web developer tools to a browser. The extension is available for Chrome and Firefox, and will run on any platform that these browsers support including Windows, OS X and Linux.

The extension can be installed from its home page:

Or directly from the Chrome and Firefox extension repositories:


For announcements about the Web Developer extension including news about beta releases and previews of upcoming versions follow:


Help for the Web Developer extension can be found on its home page:

To report a new issue or suggest a new feature please post in the forums:



The Web Developer extension is written in JavaScript, HTML and CSS. The XML user interface language XUL is also used in the Firefox version.

Extension documentation

For information about how to write browser extensions check out the Chrome and Firefox documentation:


The extension is fully localized with languages other than English (US) provided by the community. For information about how to write localized browser extensions check out the Chrome and Firefox documentation:

Build process

The extension uses the Ant build system.

Once Ant is installed the extension is built by running the following in the build directory:

ant all

To build the extension for Chrome or Firefox only run ant chrome or ant firefox in the build directory.

When the extension is built it creates a chrome and a firefox directory as well as packaged versions of the extensions and web-developer-firefox.xpi in the build directory.

The extension can be installed in Chrome by loading the unpacked extension in build/chrome as described in the Chrome documentation. The extension can be installed in Firefox by installing web-developer-firefox.xpi like a regular extension or automatically with ant install.firefox and the Extension Auto-Installer extension.

Included libraries

The following libraries are used by and included in the extension as-is:

They should not be altered apart from to update to their latest versions for maintenance reasons. The latest versions of Bootstrap from Twitter, CodeMirror and Font Awesome can be automatically merged into the repository using ant merge.bootstrap, ant merge.codemirror and ant merge.fontawesome respectively.


The icons used in the extension are:

Any new icons used in the extension should come from these existing icon sets for consistency.

Editor Configuration

An EditorConfig file is included to unify the coding style for different editors.


Chris Pederick


All files are distributed for free under the terms of the GNU General Public License. This does not apply to the included libraries or icons mentioned in the Developer section which have their own individual licenses.

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