Melvyl was the name of the online catalog of the University of California's library system. The Melvyl union catalog was produced by the California Digital Library — a unit within the department of Academic Planning, Programs, and Coordination at the UC Office of the President in downtown Oakland, California. Melvyl was named after Melvil Dewey, the library pioneer who invented the Dewey Decimal System. Melvyl was supported by the OCLC's WorldCat Local platform, which was retired in July 2021.