Plex Systems began as an internal IT project at an automotive parts manufacturer, MSP Industries Corporation, in 1989.

The company was formed as Plexus Systems LLC in 1995 by Robert Beatty,[3] providing client/server manufacturing software.

[13] Plex was the only ERP software solution provider placed entirely within the “Champion” performance category,[14] just ahead of SAP AG.

[17][18][19][20] Historically, the company has not released detailed financial information, citing its status as a privately held corporation.

[22] Several IT software bloggers have written about Plex’s ability to provide a wide scope of critical features for manufacturers in a SaaS model, where larger ERP vendors had not succeeded at the time.

This is in contrast to traditional methods that require upfront payment or financing and tend to be accounted as a capital expense (CapEx).