ClamAV was developed as an Open Source (GPL) anti-virus toolkit, especially for e-mail scanning on mail gateways.

It provides several utilities, including a flexible and scalable multi-threaded daemon, a command-line scanner, and an advanced tool for automatic database updates.

The core of the package is an anti-virus engine available in the form of a shared library. Copy the virus database packages to the "database" directory inside the main ClamAV folder.

ClamAV Features:

● POSIX compliant, portable
● Fast scanning
● Detects over 750.000 viruses, worms, and trojans, including Microsoft Office macro viruses, mobile malware, and other threats
● Built-in bytecode interpreter allows the ClamAV signature writers to create and distribute very complex detection routines and remotely enhance the scanner's functionality

Scans within archives and compressed (also protects against archive bombs), built-in support includes:

● Zip (including SFX)
● RAR (including SFX)
● 7Zip
● ARJ (including SFX)
● Tar
● CPIO
● Gzip
● Bzip2
● MS OLE2
● MS Cabinet Files (including SFX)
● MS CHM (Compiled HTML)
● MS SZDD compression format
● BinHex
● SIS (SymbianOS packages)
● AutoIt
● InstallShield

Supports Portable Executable (32/64-bit) & compressed or obfuscated with:

● AsPack
● UPX
● FSG
● Petite
● PeSpin
● NsPack
● wwpack32
● MEW
● Upack
● Y0da Cryptor
● Supports ELF and Mach-O (both 32- and 64-bit)
● Supports almost all mail formats

Support for other special formats includes:
● HTML
● RTF
● PDF
● Files encrypted with CryptFF and ScrEnc
● uuencode
● TNEF (winmail.dat)
● Advanced database updater with support for scripted updates, digital signatures and DNS based database version queries

Similar:
● What's the Best Antivirus and Is Windows Defender Good Enough?