Yesod uses Persistent for its (you guessed it) persistence layer. This tool will build in either SQLite or PostgreSQL or MongoDB support for you. We recommend starting with SQLite: it has no dependencies. s = sqlite p = postgresql pf = postgresql + Fay (experimental) mongo = mongodb mysql = MySQL simple = no database, no auth mini = bare bones, the "Hello World" of multi-file Yesod apps (Note: not configured to work with yesod devel) url = Let me specify URL containing a site (advanced) So, what'll it be?