Here you can download automated builds of RawTherapee - these include both stable releases and development builds.
For an explanation of the difference between these builds and how to read the filenames, see RawPedia:
http://rawpedia.rawtherapee.com/Download
To get the source code, either clone from git or use a .tar.xz tarball from a release.
Do not use the Source code (zip/tar.gz) tarballs auto-generated by GitHub below, they lack some metadata.