OPEN4 is the developer and owner of the OPEN4 product suite. The company started as a partnership in January 1980 and was incorporated in Texas in April of 1981. During the early years, activity was limited to consulting and custom programming.

A few years later, several mainframe software products were developed and were marketed successfully in the U.S. and Europe. In total, these products accounted for well over 600 users worldwide.

In 1989, development shifted away from mainframes to UNIX-based applications and the OPEN4 product suite was born. Migration to client/server began in 1995, with the first client installation a few years later.

On January 4, 2007, OPEN4 was purchased by UnicornHRO and became a wholly owned subsidiary of UnicornHRO.