# Castor Castor is a lightweight but full-featured gemini server, focused on ease of setup and use. Servers are configured using `Castorfile`s, analogous to Caddyfiles or nginx configurations. Various handlers can be defined: - static file serving - hard-coded responses Castorfiles also support client cert requirements; lists of client certificate hashes can be provided for authentication, or simply as session-management (hashes being passed off to a backend server for mapping to a user identity). ## Name [Castor]() is the second-brightest object in the zodiac constellation of Gemini and one of the brightest stars in the night sky, as well as one of a pair of twin half-brothers, along with his brother Pollux.