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Home/Categories/Security & Monitoring/Clamav
icon of Clamav

Clamav

Open source alternative to Sophos Endpoint, Bitdefender GravityZone, ESET Endpoint Security and Symantec Endpoint Security

  • 7.4K stars
  • GPL-2.0
  • Active recently
  • Last commit 55 days ago

Last verified Oct 22, 2026

Secure mail gateways, servers, and endpoints from trojans, viruses, and malware with ClamAV, the GPL-2.0 antivirus engine from Cisco Talos.

Visit websiteGitHub7.4K stars
Image for Clamav
TL;DR

Clamav is a GPL-2.0 open source antivirus engine maintained by Cisco Talos, used primarily in mail gateway scanning and file server protection. It detects trojans, viruses, malware, and other malicious threats, and the project describes itself as the open-source standard for mail gateway-scanning software. ClamAV includes a multi-threaded scanner daemon, command-line utilities for on-demand scanning, and automatic signature updates. It runs on Linux (Debian and RPM packages), macOS (Universal PKG installer), and Windows (MSI). Best for sysadmins and security teams running mail gateways, file servers, or infrastructure requiring self-hosted antivirus scanning without recurring licensing costs.

Read the full breakdownHide the full breakdownWho it is for, how it works, trade-offs, the quick start and the FAQ
who it's for

Who Clamav is for#

Mail gateway admins scanning email attachments

ClamAV is described as the open-source standard for mail gateway-scanning software. The multi-threaded daemon handles ongoing scan workloads, and archive unpacking catches compressed malicious attachments before they reach end users.

Skip if:

Your mail gateway is cloud-managed (Google Workspace, Microsoft 365). Those platforms handle attachment scanning natively.

Sysadmins securing file servers and shared storage

Run the command-line scanner on a schedule or triggered by file events to scan for malware on shared storage. Linux packages and the official Docker image make deployment straightforward on standard Linux file servers.

Skip if:

You need enterprise fleet management across many endpoints rather than server-level file scanning.

Security teams building file inspection pipelines

ClamAV's command-line interface and scanning daemon integrate into CI/CD artifact scanning or custom file inspection workflows. Teams can author custom signatures using the signature languages ClamAV supports and deploy them alongside the standard database.

Skip if:

Your pipeline requires capabilities beyond static file and archive scanning, such as dynamic behavioral analysis.

the problem

The problem it solves#

Mail gateways and file servers need scanning coverage to catch trojans, viruses, and malicious file attachments before they reach users. Paid, proprietary endpoint security products require licensing fees for each covered installation, adding recurring costs as infrastructure grows.

For teams running Linux mail servers or shared file storage, a self-hosted open source scanning engine avoids commercial licensing overhead. ClamAV provides a scanning engine, automatic signature updates, and cross-platform packages that cover the detection use case without a subscription.

how Clamav solves it

How it solves it#

Multi-threaded scanning daemon

The multi-threaded scanner daemon runs as a persistent background service, handling scan workloads across multiple threads. This makes it well suited for continuous mail gateway and file server scanning where requests arrive in parallel.

CLI scanner for on-demand file scanning

Command-line utilities scan individual files, directories, or streams on demand. Useful for scripted integrity checks, scheduled scan jobs, or one-off file verification. Available on Linux, macOS, and Windows.

Automatic signature updates

ClamAV includes automatic signature update utilities that download the latest detection signatures on a configurable schedule. The project maintains the signature database independently of the engine release cycle, so coverage stays current between engine upgrades.

Custom signature writing

ClamAV supports multiple signature languages, allowing custom detection rules to be authored and deployed alongside the standard database. The signature writing manual is published at docs.clamav.net, and anyone can contribute signatures.

Multiple file format support with archive unpacking

The engine supports multiple file formats and handles archive unpacking before scanning their contents. RAR support is provided by an optional component (libclamunrar) that loads separately at runtime due to its license terms.

strengths · trade-offs

Strengths and trade-offs#

Strengths

  • GPL-2.0 licensed with no recurring licensing feesClamAV is free to run on any number of servers under the GPL-2.0 license. Unlike paid, proprietary endpoint security alternatives, there are no recurring licensing costs as infrastructure scales. The GPL-2.0 license permits use in commercial infrastructure for internal scanning.
  • Open-source standard for mail gateway scanningThe ClamAV website describes the project as the open-source standard for mail gateway-scanning software. Packages are available for all major Linux distributions, making the engine directly applicable to Linux-based mail server infrastructure.
  • Cisco Talos maintenanceClamAV is maintained by Cisco Talos (GitHub: Cisco-Talos/clamav). The signature database updates independently of the engine release cycle, so detection coverage stays current between engine version upgrades without requiring operators to upgrade the engine itself.
  • Cross-platform with official Docker imageRuns on Linux (Debian and RPM packages for x86_64 and i686), macOS (Universal PKG installer for x86_64 and arm64), and Windows (MSI installers and portable ZIP). An official Docker image is available on Docker Hub (clamav/clamav).

Trade-offs

  • -No built-in management consoleClamAV has no built-in dashboard or management console. Configuration, scan scheduling, log review, and signature status tracking all require CLI access or integration with external monitoring tools. Teams that need centralized visibility will need to build it around ClamAV's logging output.
  • -Scanning engine, not a security management platformClamAV is a scanning engine and command-line toolset, not a full security management platform. Organizations that need centralized policy enforcement, fleet visibility, or security features beyond file and mail scanning need to source those capabilities from other tools.
  • -420 open issues and optional RAR supportThe GitHub repository has 420 open issues. RAR archive scanning requires an optional component (libclamunrar) that is not linked at build time due to license incompatibility with GPLv2. If libclamunrar fails to load at runtime, ClamAV continues operating without RAR support.
versus alternatives

Clamav vs alternatives#

ClamAV vs Sophos Endpoint

Sophos Endpoint is a paid, proprietary commercial endpoint security product. ClamAV is a GPL-2.0 open source antivirus engine with no licensing fees.

ClamAV covers file and mail gateway scanning: the project website describes it as the open-source standard for mail gateway-scanning software, and it installs on Linux, macOS, and Windows via native packages or Docker. Sophos Endpoint is a commercial platform sold under a proprietary license, targeting enterprise endpoint environments.

For Linux mail gateway environments where self-hosting and zero recurring cost are requirements, ClamAV is the appropriate choice. Sophos Endpoint serves organizations that need a commercial endpoint security platform with vendor support and enterprise management capabilities.

ClamAV vs Bitdefender GravityZone

Bitdefender GravityZone is a paid, proprietary endpoint security product. Like Sophos Endpoint, it is a commercial platform aimed at enterprise endpoint environments.

ClamAV's GPL-2.0 license means no recurring licensing costs. The engine covers file and mail scanning and is maintained by Cisco Talos. For teams whose core need is mail gateway or file server scanning on Linux at no cost, ClamAV is the relevant choice. Bitdefender GravityZone serves organizations that need a full commercial endpoint security platform with vendor support.

ClamAV vs ESET Endpoint Security

ESET Endpoint Security is a paid, proprietary commercial endpoint security product. ClamAV is open source under GPL-2.0.

The two products target different deployment models: ClamAV is always self-hosted with no managed service tier, focusing on file and mail gateway scanning. ESET Endpoint Security is a commercial platform with vendor licensing and support. Organizations that need self-hosted, GPL-2.0 licensed antivirus scanning without commercial licensing overhead fit ClamAV's deployment profile; organizations that need a managed commercial endpoint security product are in ESET's target market.

install · quick start

Quick start#

bash
Install ClamAV using Docker with the official image from Docker Hub.
```bash
docker pull clamav/clamav
docker run -d clamav/clamav
```
tech stack · detected from GitHub

What it's built on#

Languages
CC++PythonRust
frequently asked

FAQ#

Is ClamAV a replacement for commercial endpoint protection software?

For mail gateway scanning and file server use on Linux, ClamAV is a production-ready open source choice. For broader endpoint protection needs that include management consoles, policy enforcement, or platform features beyond file scanning, commercial endpoint security products offer capabilities ClamAV does not include. The right choice depends on the specific deployment scenario.

Does ClamAV run on Windows and macOS?

Yes. ClamAV provides MSI installers for Windows (32-bit and 64-bit) and a Universal PKG installer for macOS (x86_64 and arm64). Installation packages are available from the downloads page at clamav.net, and installation instructions for each platform are at docs.clamav.net.

How often does ClamAV update its virus signatures?

Signature updates run on a configurable schedule. The project maintains the signature database independently of the ClamAV engine release cycle, so threat coverage updates without requiring an engine upgrade.

Can I run ClamAV in Docker?

Yes. An official Docker image (clamav/clamav) is available on Docker Hub. The README points to docs.clamav.net under the Docker section for full setup instructions, and images are also browsable directly on Docker Hub.

Can I write custom antivirus signatures for ClamAV?

Yes. ClamAV supports multiple signature languages, and anyone can learn to read and write ClamAV signatures. The signature writing manual is published at docs.clamav.net. Custom signatures can be authored and loaded alongside the standard database.

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