Phabricator is built here, by Phacility. For an overview of how the upstream works, see the Welcome page. If you have questions about Phabricator, join our Discussion Forum. If you are a Phacility customer or have a paid support contract and need help, please file a request from your account on Phacility.
NOTE: You can launch a test installation of Phabricator on Phacility if you want to poke around and try things out.