The Online Historical Encyclopaedia of Programming Languages (HOPL) presents a comprehensive roster of 8945 programming languages, spanning from the 18th century to the present day. This extensive resource meticulously details 7,800 influence links and cites over 11,000 references, offering a rich genealogical tree of programming language evolution.

The site features sections on advanced search, navigation, and the rationale behind the Gernsback Machine. It delves into the definition of computer languages, providing analysis, reports, and a taxonomy of language genealogy.

Key contributors include Diarmuid J Pigott, responsible for the incunabula period up to 1989, and Bruce M Axtens, covering 1990 to the present. Steve Poulson manages the programming (sim) aspect. The content is copyrighted by Diarmuid Pigott and reproduction is prohibited. Errata and notifications can be sent to [email protected].