ClamAV

ClamAV is an open-source antivirus toolkit maintained by Cisco Systems, Inc. It was first publicly released on May 8, 2002, by creator Tomasz Kojm.

The project focuses on email gateway scanning, file inspection, and malware detection. It includes the libclamav scanning engine, the clamd multi-threaded daemon, the clamscan command-line scanner, and the freshclam signature updater.

ClamAV is not a full commercial endpoint security suite. Its Linux client supports on-access scanning, while Windows and macOS primarily provide on-demand scanning capabilities.

ClamAV scans common mail formats, archives, compressed files, Windows Portable Executables, ELF binaries, Mach-O files, Office documents, PDFs, HTML, RTF, and several disk-image formats.

The platform includes signed signature databases, bytecode signatures, archive-bomb protection, automatic database updates, and support for multiple signature formats. The official database is updated multiple times per day.

clamd provides a persistent scanning service for applications and infrastructure. clamdscan, clamonacc, clamav-milter, clamdtop, sigtool, clambc, and freshclam provide scanning, mail filtering, monitoring, signature testing, and update functions.

ClamAV is available at no software license cost under the GNU General Public License, version 2. There are no published paid tiers, per-user fees, or hosted subscription plans on the official website.

Organizations remain responsible for deployment, infrastructure, configuration, database management, monitoring, and support. A free trial is not applicable because the software can be downloaded and used directly under its open-source license.

Pros

• No license fee for the GPLv2 software.
• Supports email gateways, command-line workflows, daemons, and custom integrations.
• Runs across Linux, Windows, macOS, FreeBSD, and other Unix-like environments.
• Provides broad archive, document, executable, and disk-image parsing.
• Offers both a C library API and a socket-based daemon protocol.

Cons

• Deployment and configuration require command-line and systems administration skills.
• Linux provides the documented on-access scanning capability; Windows and macOS do not provide the same feature.
• It is not a complete modern endpoint security suite with centralized management.
• TCP connections to clamd are not encrypted or authenticated by the daemon.
• libclamav’s GPLv2 licensing can restrict linking with closed-source commercial software.

Linux Malware Detect is a comparable file-scanning tool for Linux servers. Sophos Protection for Linux and ESET Server Security provide commercial Linux malware protection with vendor support.

Microsoft Defender for Endpoint and Bitdefender GravityZone are broader commercial endpoint security platforms. YARA is a complementary pattern-matching framework rather than a direct replacement for ClamAV’s antivirus engine.

Is ClamAV free?

Yes. ClamAV is distributed under GPLv2 without a published software license charge.

Does ClamAV provide an API?

Yes. Developers can use the libclamav C API or connect applications to clamd through its Unix or TCP socket protocol.

Which operating systems does ClamAV support?

Officially tested platforms include GNU/Linux distributions, FreeBSD, macOS, and Windows. Support varies by release and architecture.

Does ClamAV provide real-time protection?

ClamOnAcc provides on-access scanning through clamd on modern Linux systems. The official documentation does not describe equivalent built-in on-access support for Windows or macOS.

Can ClamAV scan email?

Yes. ClamAV supports mail formats and includes a milter interface for Sendmail-based email processing.

Does ClamAV disinfect infected files?

No. The official FAQ states that ClamAV does not disinfect files.