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Revision as of 01:57, 19 December 2004

This page is part of the extension development documentation project.

Ask your questions in MozillaZine Forums. Also try browsing example code.

Note: development documentation is in process of being moved to Mozilla Development Center (MDC).


Packaging extensions for Firefox and Thunderbird

Firefox 0.9, Thunderbird 0.7 and all subsequent versions of these products use the new Extension Manager feature. In order to be supported by it you have to package your extensions as described in this document.

Creating install.rdf for your extension using tools

You can use any of these tools:


Alternatively you can create it from template below.

<?xml version="1.0"?>
<RDF xmlns="" xmlns:em="">

	<Description about="urn:mozilla:install-manifest">
		<em:name>Sample Extension</em:name>
		<em:description>A sample extension with advanced features</em:description>
		<em:creator>Your Name Here</em:creator>
		<!-- optional items -->
		<em:contributor>A person who helped you</em:contributor>
		<em:contributor>Another one</em:contributor>

			<Description about="urn:mozilla:extension:file:sampleext.jar">
				<!-- optional items -->

		<em:targetApplication> <!-- Firefox -->
 		<em:targetApplication> <!-- Thunderbird -->
 		<em:targetApplication> <!-- Mozilla Suite -->



Mozilla Suite currently ignores install.rdf, but you ought to include corresponding targetApplication item in install.rdf if you support The Suite and are going to submit your extension to, see this thread. You must include an install.js file if you support Mozilla Suite.

Generating a GUID

You’ll have to generate a GUID for each extension you create and put it inside the <em:id> tag. You can either download MS guidgen (a Windows GUID generator), use uuidgen (for *nix), or open your IRC client, go to irc:// and say 'botbot uuid'.

As Firefox/Thunderbird install each extension in a folder with name taken from <em:id> in install.rdf, some people (e.g. clav) are using human-readable strings as ID for their extensions. However, extensions with such IDs are reported to be rejected by, so you need to use a 'real' GUID for your extension if you're going to submit it to u.m.o. (discussion thread)

Extension versioning

As stated in the official documentation on, extension versions must be of form[+]. Old-style versions like 0.5pre are now invalid.