XenForo is an Internet forum software package written in the PHP programming language.

The original owner of vBulletin, Jelsoft, was acquired by the American new media company Internet Brands in 2007.

[3][4] One day before the scheduled release of the first public beta of XenForo in October 2010, Internet Brands announced that it would file a lawsuit against the XenForo team in the UK, claiming: copyright infringement of property acquired by Internet Brands, use of code in XenForo that was refactored from vBulletin code, breach of contract, and engaging in unfair business practices.

In November 2010, Internet Brands sued XenForo and Darby in California District Court in the United States, additionally claiming that Darby had not returned confidential information from Internet Brands regarding the vBulletin software.

Although specific terms of the agreement are confidential, Internet Brands withdrew both the US and UK lawsuits.