Clam AntiVirus (ClamAV) is a free and open source, cross platform antivirus toolkit able to detect many types of malicious software, including viruses. One of its main uses is on mail servers as a server-side email virus scanner. The application was developed for Unix and has third party versions available for AIX, BSD, HP-UX, Linux, OS X, OpenVMS, OSF (Tru64) and Solaris.
As of version 0.97.5, ClamAV builds and runs on Microsoft Windows. Both ClamAV and its updates are made available free of charge.
ClamAV is a powerful AntiVirus scanner focused towards integration with mail servers for attachment scanning. It provides a flexible and scalable multi-threaded daemon, a command line scanner, and a tool for automatic updating via the Internet.
Clam AntiVirus is based on a shared library distributed with the Clam AntiVirus package, which you can use with your own software. Most importantly, the virus database is kept up to date. The project was acquired by Sourcefire in 2007
ClamAV includes a number of utilities: a command-line scanner, automatic database updater and a scalable multi-threaded daemon, running on an anti-virus engine from a shared library.
The application also features a Milter interface for sendmail and on-demand scanning. It has support for Zip, RAR, Tar, Gzip, Bzip2, OLE2, Cabinet, CHM, BinHex, SIS formats, most mail file formats, ELF executables and Portable Executable (PE) files compressed with UPX, FSG, Petite, NsPack, wwpack32, MEW, Upack and obfuscated with SUE, Y0da Cryptor. It also supports many document formats, including Microsoft Office, HTML, Rich Text Format (RTF) and Portable Document Format (PDF).