CVMFS is a FUSE module which implements an HTTP read-only filesystem. The idea is based on GROW-FS. GROW-FS filesystem makes part of Parrot in the CC Tools developed at the University of Notre Dame. CVMFS shows a remote HTTP directory as local file system. The client sees all available files. On first access, a file is downloaded and cached locally. All downloaded pieces are verified with SHA-1. To do so, a directory hive has to be transformed into a CVMFS "repository", a form of content-addressable storage. This preparation of directories is transparent to web servers and web proxies. They just serve static content, i.e. arbitrary files. Any HTTP server should do the job. Developed for the delivery of experiment software stacks of the LHC experiments at CERN.