The Advanced Intrusion Detection Environment (AIDE) was initially developed as a free replacement for Tripwire licensed under the terms of the GNU General Public License (GPL). The primary developers are named as Rami Lehti and Pablo Virolainen, who are both associated with the Tampere University of Technology, along with Richard van den Berg, an independent Dutch security consultant. The project is used on many Unix-like systems as an inexpensive baseline control and rootkit detection system.