Ninenines is a technology company specializing in the development and maintenance of open-source software related to the Erlang ecosystem. They are particularly known for their work on the Cowboy web server, a small, fast, and modular HTTP server written in Erlang. Additionally, Ninenines offers other tools and libraries that are widely used in the Erlang community for building efficient and scalable web applications and services. Their website, http://ninenines.eu, provides access to documentation, source code, and other resources for developers looking to leverage Erlang for their projects.