Best Open-Source Antivirus Tools 2026: 6 Options Compared

Open-source antivirus is a smaller field than the commercial one, and it is worth being honest about what you get. ClamAV is the established open-source scanning engine. It is widely used on mail servers and Linux machines, and it scans files on demand, but it lacks the real-time protection and polished interface of consumer products on Windows. ClamTk puts a graphical front end on ClamAV for the Linux desktop. YARA is a rule language for identifying malware families in files, used by analysts rather than by everyday users. Wazuh, Velociraptor and osquery are endpoint monitoring and investigation tools: they watch hosts, collect evidence and raise alerts, which is closer to endpoint detection than to a home antivirus. The trade-off is this: if you want install-and-forget protection on Windows, Microsoft Defender or a commercial product will be less work, and the open-source options here suit servers, Linux workstations, mail gateways and security teams who are willing to assemble their own stack. Whichever route you pick, keep signature updates running, because an out-of-date scanner gives false confidence. For a mixed fleet, pair a scanner with a monitoring platform such as Wazuh so you can see what is happening across machines, not only scan files one at a time.

ClamAV

The main open-source antivirus engine under GPL-2.0. Good for on-demand scans and mail servers, but it does not give consumer-style real-time protection by itself.

Price: Free (ClamAV pricing, checked 2026-10-22).

Platforms and license: Linux, Windows, macOS. GPL-2.0 (open source) (license source).

Project activity: 7.5k GitHub stars · latest release clamav-1.5.4 (Aug 7, 2026) · last commit Oct 22, 2026

Best for: Linux servers and mail scanning.

Worth knowing: Scanner and signature updates only; no central console or behavioural EDR.

ClamTk

Graphical front end for ClamAV on Linux. Offers GPL or Artistic License terms, and inherits ClamAV's detection and its limits.

Price: Free (Free open source) (ClamTk pricing, checked 2026-10-24).

Platforms and license: Linux. GPL (v1 or later) or Artistic License (open source) (license source).

Project activity: 440 GitHub stars · latest release v6.18 (Jan 27, 2024) · No commits since Mar 30, 2024

Best for: Linux desktop users who want a window.

Worth knowing: Graphical scanner for ClamAV; the LICENSE file offers GPL (version 1 or later) or the Artistic License.

YARA

BSD-3-Clause rule-matching tool for classifying malware samples. It is for analysts writing rules and not an on-access scanner.

Price: Free (Free open source) (YARA pricing, checked 2026-10-24).

Platforms and license: Linux, macOS, Windows. BSD-3-Clause (open source) (license source).

Project activity: 10k GitHub stars · latest release v4.6.0 (Oct 27, 2026) · last commit Oct 27, 2026

Best for: Analysts classifying malware.

Worth knowing: Rule-matching tool for classifying malware samples; it is not an on-access scanner.

Wazuh

Open-source security monitoring platform with endpoint agents, mostly GPL-2.0. Free with no license cost; paid support and cloud are not priced on the page.

Price: Free (free, no license cost; paid support and cloud not priced on the page) (Wazuh pricing, checked 2026-10-22).

Platforms and license: Windows, Linux, macOS, Self-hosted. GPL-2.0 (most code); AGPL-3.0 (engine) (open source) (license source).

Project activity: 17.5k GitHub stars · latest release v4.14.9 (Oct 15, 2026) · last commit Oct 27, 2026

Best for: Monitoring many hosts.

Worth knowing: XDR/SIEM with host agents; free cloud trial.

Velociraptor

AGPL-3.0 endpoint visibility and incident-response tool for collecting evidence at scale. A hunting tool, not a set-and-forget scanner.

Price: Free (Velociraptor pricing, checked 2026-10-22).

Platforms and license: Windows, Linux, macOS. AGPL-3.0 (open source) (license source).

Project activity: 4.4k GitHub stars · latest release v0.77.3 (Oct 5, 2026) · last commit Oct 27, 2026

Best for: Incident response teams.

Worth knowing: Endpoint visibility, hunting and DFIR collection, not a prevention agent.

osquery

Apache-2.0 or GPL-2.0 tool that exposes the operating system as a SQL database so you can query processes and files. Useful for detection, but not an antivirus on its own.

Price: Free (osquery pricing, checked 2026-10-22).

Platforms and license: Windows, Linux, macOS. Apache-2.0 OR GPL-2.0-only (open source) (license source).

Project activity: 23.7k GitHub stars · latest release 5.24.0 (Oct 9, 2026) · last commit Oct 27, 2026

Best for: Querying hosts for suspicious state.

Worth knowing: SQL-style endpoint telemetry; no blocking or response on its own.

Which one to pick

• You want to scan a Linux machine or mail server: ClamAV
• You want a graphical scanner on a Linux desktop: ClamTk
• You need to watch many machines for threats: Wazuh
• You are investigating a compromised host: Velociraptor