Sleepycat Software, Inc. develops, and supports Berkeley DB. Berkeley DB was originally written by Keith Bostic, Mike Olson, Margo Seltzer, and Ozan Yigit in the early 1990s. Keith Bostic, one of the principal developers of the University of California's 4.4BSD UNIX releases, approached Seltzer and Yigit to write an Open Source implementation of the UNIX C library dbm hash package for inclusion in 4.4BSD. They agreed, and created a general-purpose hashing library. Later, Bostic enlisted Olson to add a Btree access method to the package. These two projects were integrated and became the first Berkeley DB release, which was included in the 4.4BSD UNIX and related Net/2 releases. In the years that followed, Berkeley DB was adopted by an enormous number of both proprietary and Open Source projects. Its high performance, ready availability, and easy-to-use interfaces made it a natural tool for a wide variety of applications. In 1996, there were enough commercial users of the software to justify the formation of a company to enhance and support it. Bostic and Seltzer formed Sleepycat Software to do this. They spent a year adding critical features to the academic code (most notably, transactions, support for concurrent users, and recoverability), and version 2.0 of Berkeley DB was released by Sleepycat Software in 1997. Since that initial release, Berkeley DB has been deployed in network switches, email clients, wireless communication systems, mission-critical site-monitoring software, and many other applications. Sleepycat is an Open Source company, and it is committed to the development and distribution of Berkeley DB as an Open Source product. Sleepycat's license for Berkeley DB permits its use at no charge in Open Source applications.