Today the source code for jam.ludumdare.com can be found built-in to Jammer Core. You can find that here:
https://github.com/JammerCore/JammerCore
In the future, this will project will contain Ludum Dare's customizations to the JammerApp project.
If you need support, you can find our support website here:
https://ludumdare.com/support/
If you find bugs or issues with the website, file them on the Jammer Core project.