In addition to the source archive from a release, the source code is hosted on a public subversion repository kindly sponsored by mgm technology partners.

The repository is located at http://sqlworkbench.mgm-tp.com and can be accessed through a web-browser or by checking it out with svn.

To read or checkout the sources you don't need a username.

I recommend to only check out the trunk. If you include the tags directory as well, you get all the release from the last 5 years...