The nightly build of DDNet from its source code has been revived: https://ddnet.tw/news/nightly-build-revived/
You can use these nightly builds to try out new DDNet features before they’re released and report problems and suggestions. The nightly client does not auto-update, instead you will get a notification when a new regular DDNet version has been released.
You can also opt into the beta release of DDraceNetwork on Steam to automatically get a new test version every day.
Please report any problems you have with the nightly build on this Discord or directly on GitHub: https://github.com/ddnet/ddnet/issues