GuardLabs

← All website monitoring tools

Open-Source (7 options, 2026)

Self-hosted, code-on-GitHub options. Run on your own server, customize freely, never pay per-site fees.

OWASP ZAP

OWASP ZAP

free from $0/mo

Most popular free open-source DAST scanner — active/passive web scanning, intercepting proxy, CI/CD integration.

web-appapidastopen-sourcefree-tier
Greenbone / OpenVAS

Greenbone / OpenVAS

freemium from $0/mo

Open-source vulnerability scanner descended from Nessus — free Community Edition, paid appliances for enterprise.

networkvuln-managementopen-sourcefree-tiersmall-team
Nuclei (ProjectDiscovery)

Nuclei (ProjectDiscovery)

free from $0/mo

Template-driven fast scanner — community templates cover thousands of CVEs. Free CLI, paid managed cloud.

web-appapidastopen-sourcefree-tier
Nikto

Nikto

free from $0/mo

Long-running open-source web server scanner — checks 6,700+ dangerous files and outdated software.

web-appdastopen-sourcefree-tiersolo
Nmap

Nmap

free from $0/mo

Standard network discovery + port/service scanner — universal first step for any audit.

networkreconopen-sourcefree-tiersolo
Wazuh

Wazuh

freemium from $0/mo

Open-source SIEM/XDR with file-integrity, vuln detection, compliance audit modules — also paid Wazuh Cloud.

siemcompliancemonitoropen-sourcefree-tier
WPScan

WPScan

freemium from $0/mo

WordPress-specific vulnerability database + scanner — free CLI with optional API key.

wordpressvuln-managementopen-sourcefree-tiersolo

Tips for open-source tools