This project uses Git to manage its source code. Instructions on Git use can be found at http://git-scm.com/documentation.
The source can be checked out anonymously from Git with this command (See http://git-scm.com/docs/git-clone):
$ git clone --branch zxing-3.3.1 https://github.com/zxing/zxing.git
Only project developers can access the Git tree via this method (See http://git-scm.com/docs/git-clone).
$ git clone --branch zxing-3.3.1 https://github.com/zxing/zxing.git