One of the developers of XenForo, Kier Darby originally served as a lead developer for the community platform vBulletin. The original owner of the software, Jelsoft, was acquired by the American new media company Internet Brands in 2007. Disagreements between the lead developers and the new management over matters involving the next big release of vBulletin, version 4.0 (including a rejection of their desire to make 4.0 a complete rewrite of the platform as opposed to Internet Brands preferring the use of agile development) led most of the original vBulletin developers to step down from employment at Internet Brands in 2009.