MirrorBrain is a framework to run a content delivery network using mirror servers. It solves a challenge that many popular open source projects face: a flood of download requests, often magnitudes more than a single site could practically handle. A central (and probably the most obvious) part is a "download redirector" that automatically redirects requests from Web browsers or download programs to a mirror server near them. Choosing a suitable mirror for a user's request is the key, and MirrorBrain uses geolocation and global routing data to make a sensible choice and achieve load-balancing for the mirrors at the same time. The algorithm is both sophisticated and easy to control and tune. In addition, MirrorBrain monitors mirrors, scans them for files, generates mirror lists, and more.