Clam AntiVirus is an anti-virus toolkit written from scratch. It is licensed
under GNU GPL2 and uses the virus database from OpenAntiVirus, which is an
another free anti-virus project. In contrast to OpenAntiVirus (which is written
in Java), Clam AntiVirus is written entirely in C and its database is KEPT UP
TO DATE. It also detects polymorphic viruses as well.

Homepage:
https://www.clamav.net/
