The latest release of Protocol Buffers is 3.0.0. It was released on July 27, 2016. See the release page for release notes and downloads.
We recommend users to use the latest version. If you still need an old version for some reason, you can find our historical releases here.
Protocol Buffers source code is hosted on GitHub: https://github.com/google/protobuf.
Google Code Repostiory
Our old Google Code repository is: https://code.google.com/p/protobuf/. We moved to GitHub on Aug 26, 2014 and no future changes will be made on the Google Code site. For latest code updates/issues, please visit our GitHub site.