Documentation
Getting the source
The source code of the current stable release is available on the download page. Source snapshots from previous releases and beta versions are available from the project page at SourceForge.net.
Alternatively, you can check out the source code from the project's Subversion repository. The repository URL is https://filezilla.svn.sourceforge.net/svnroot/filezilla/FileZilla3
To get the most recent source you want to check out the development trunk:
svn co https://filezilla.svn.sourceforge.net/svnroot/filezilla/FileZilla3/trunk filezilla
Previous releases have been tagged in the repository, for example to check out the source for version 3.0.8-rc1 type
svn co https://filezilla.svn.sourceforge.net/svnroot/filezilla/FileZilla3/tags/3.0.8-rc1 filezilla-3.0.8-rc1
You can also browse the SVN repository online.