Skwish is a fast, simple, lightweight Java library for storing blobs on the file system. It allows multiple concurrent readers and writers, provides all-or-nothing write semantics, and is designed to survive abnormal, unclean shutdown. Skwish is a structured implementation of storing all blobs in a single file to save on file system I/O. Skwish is premised on the proposition that blob storage ought to be orthogonal to the task of indexing. It is meant to be a clean and simple store on which some other index can be built.