ClamAV is an open source antivirus solution that features a command line interface for scanning files, updating the virus definitions, and a daemon for faster scanning needed on high performance systems.

Unlike most antivirus products, ClamAV requires no yearly subscription fee, and is completely free with source code to anyone who wishes to use it. Because it is released under the GPL v2 license, you must follow all license requirements if you modify the ClamAV source code, or use it in your own projects.