Documentation & Resources

A collection of the most important developer resources outside of developer.thunderbird.net.

MailExtension Development

A few helpful resources relevant for developing add-ons for Thunderbird.

	Description
addons.thunderbird.net	The official Thunderbird add-on repository.
List of Thunderbird app versions	A list of all supported values, which can be used as strict_min_version and strict_max_version values in add-on manifest files.
Debugging Guide	A guide from the extension workshop with the most recent information on debugging add-ons. It is written for Mozilla Firefox but applies for Thunderbird as well.
Supercharge your Thunderbird extension debugging	A guide how to use Visual Studio Code to debug Thunderbird extension.
WebExtension API Documentation for Thunderbird	Documentation of all WebExtension APIs supported by Thunderbird. Thunderbird Beta (MV3, MV2) Thunderbird 128 (MV3, MV2) Note: The documentation for Thunderbird 128 and newer are available for Manifest Version 3 (MV3) and Manifest Version 2 (MV2).
Thunderbird WebExtension Examples	A collection of explanatory WebExtension examples for Thunderbird.
Firefox WebExtension Examples	A collection of WebExtension examples for Firefox and other browsers. They probably won’t work directly in Thunderbird, but they may provide hints on how to use some of the WebExtension APIs that Thunderbird inherited from Firefox.
Thunderbird WebExtension Support Repository	The WebExtension support repository provides additional tools, scripts, custom elements, Experiment APIs and other resources, to simplify the development of WebExtensions for Thunderbird.
Bugzilla	Central bug tracking for Mozilla projects. Some useful pages related to Thunderbird: List of bugs related to Extension APIs List of all Thunderbird Components
Mozilla Developer Documentation (MDN)	The main documentation for Mozilla developers. As Thunderbird is based on the Mozilla platform, some Mozilla documentation is valid for Thunderbird as well. Useful MDN pages on WebExtension are: Introduction to WebExtensions manifest.json permissions

Experiment Development

Useful resources for converting legacy extensions or for creating Experiments.

	Description
Searchfox	An online viewer to search the Firefox code base (mozilla-central) and the Thunderbird code base (comm-central).
Firefox Source Tree documentation	The current Firefox code documentation, which might be needed when converting legacy extensions.
Thunderbird Source Tree documentation	The current Thunderbird code documentation, in addition to comments in idl files on comm-central. This is still work in progress.
Archived XUL and XPCOM Documentation	The archived Mozilla documentation includes information about internal components and functions used by legacy extensions. Please be aware, that those pages are not maintained and are potentially outdated. Some useful direct links: Archived JavaScript Code Modules Archived XUL Documentation Archived XPCOM Interface Reference