Evi (formerly True Knowledge) is a technology company in Cambridge, England, founded by William Tunstall-Pedoe, which specialises in knowledge base and semantic search engine software. Its first product was an answer engine that aimed to directly answer questions on any subject posed in plain English text, which is accomplished using a database of discrete facts. The True Knowledge Answer engine was launched for private beta testing and development on 7 November 2007. The company changed its name from True Knowledge to Evi in June 2012.