.CIRC File Extension
What is a CIRC file?
Circuit file created and used by Logisim, a graphical tool for designing and simulating logic circuits; contains circuit data in XML format; includes names and placement coordinates of wiring, gates, and plexers.
Logisim is primarily used by college students in a variety of disciplines from computer organization courses to logic in general education classes. As of October 11, 2014 development of Logisim has been suspended indefinitely.