Download Mozilla Source Code

The Mozilla source code can be obtained either by downloading a source archive, or by using a CVS (source control) client. If you are just starting out, or you wish to build a particular Mozilla product release, downloading a source archive is recommended. Otherwise, get the Mozilla Source Code Via CVS.

Before attempting a build, please review the system requirements and build instructions.


This code is covered by the Netscape Public License and Mozilla Public License. Please read the terms of these licenses before altering or copying the source code.



The source code for a release can be found on the FTP server in the "source" subdirectory of the release you want to acquire. The directory structure on the FTP server is as follows:


where names not in all uppercase are verbatim. PROJECT has to be replaced by e.g. firefox or thunderbird, and RELEASE by e.g. or bonecho. The base for such a path is Some projects do not provide source code via FTP e.g. bonsai - in this case, you should use CVS (if possible).

The easiest way to find the source code of the release you want is to start at, and navigate your way through to it, bearing in mind the directory structure convention listed above. To navigate the FTP server, use either a browser like Firefox or an FTP client of your choice.

For example, the Firefox source code can be found in

The entire source tree is not available for download over FTP.


At the moment, source tarballs of the nightly snapshots are not provided. Currently we don't have nightly source tarballs: You can download a trunk nightly source tarball from where? This tarball will have the CVS files prepopulated so that the tarball can be updated from anonymous CVS.


Source code is packaged as bzipped tarballs. This means that you must have tar along with bzip2 installed, since the -j flag in the commands listed below means the archive is first being unpacked with bzip2. To unpack a tarball from a unix-like shell (or the cygwin shell), type:

tar -xjf <source-file.tar.bz2>

Or, if you want to see the files extracted,

tar xjfv <source-file.tar.bz2>

Note for Windows users: using WinRAR or WinZip to unpack source archives will not work. WinZip does not support *.bz2 files, and the archive contains zero-length files which are not unpacked properly. For windows, use for example 7-zip software.


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