(1) An earlier family of client/server development tools for Windows and OS/2 from Ardent Software (formerly VMARK). It was originally developed by Easel Corporation, which was acquired by VMARK. ESL included a screen scraper for turning character-based screens into GUI front ends and was often used to develop systems that incorporated the mainframe. In 2000, Informix acquired Ardent.

(2) (Electronic Software Licensing) Software that keeps track of the number of active users per application in order to comply with the multiuser licensing contracts that have been purchased.