Source code for all Mozilla projects hosted in the Mercurial and CVS repositories can be searched and viewed online using MXR. It's a hacked variant of the original Linux Cross Reference tool.
Some other MXR roots of interest are:
- "mozilla-central" contains current Firefox and Gecko development. Releases branch off of this repository. Also known as "Trunk" .
- "comm-central" contains current Thunderbird, SeaMonkey and Calendar development. Also contains a mirror of mozilla-central. Releases branch off of this repository.
- "mozilla-1.9.1" contains Branch development on Firefox 3.5 and Gecko 1.9.1.
- "comm-1.9.1" contains Branch development for Thunderbird 3, SeaMonkey 2 and Sunbird 1 with Gecko 1.9.1. Also contains a mirror of mozilla-1.9.1.
- "mozilla" root contains the 1.9 branch code, like "seamonkey", but indexes a bigger part of the repository and is updated less often.
- Mozilla 1.8 root contains Firefox, Thunderbird 2.0.0.x, and SeaMonkey 1.1.x
- Mozilla 1.8.0 root contains Firefox, Thunderbird 1.5.0.x, SeaMonkey 1.0.x
- Aviary 1.0.1 root Firefox and Thunderbird 1.0.0.x
- Mozilla 1.7 root contains Mozilla Suite 1.7.x
Mozilla Source Code Directory Structure has a short description of the code living in each source directory of the tree.