chess4j is a Java based chess program.
Download
You can download the source code as well as the release bundle from the chess4j Github repo: https://github.com/jswaff/chess4j
chess4j is distributed under the MIT license. See LICENSE.TXT in the download for details, but essentially it means you can do pretty much anything you want with chess4j as long as (1) you don’t hold me liable, and (2) you provide attribution back to me.