vBulletin was the forum software which Facepunch runs on. Facepunch previously used a highly modified version of vBulletin 4, but also formerly ran on various versions of vBulletin 3. The forum was so heavily modified that, from 2006 to 2009, there was a disclaimer at the bottom of the forums warning readers not to "buy vBulletin and expect it to be as awesome as this modified board is."
On the 15th of March of 2018, vBulletin was phased out in favour of the New Sites Forum which ran on custom software.
- Wayback Machine - Facepunch (October 24th, 2006) [external link]: http://web.archive.org/web/20061024005032/http://forums.facepunchstudios.com/