No. 4 of 30 ·Web Application Firewall Software

ModSecurity

Windows · Mac · Linux · Self-hosted

Freedom report

Three barsScore 6.4

Free tierA free tier is on its own pricing page
Open codeNo open-source code on record
Runs widely3 of 6 device platforms
DocumentedPlans, terms and facts published

ModSecurity is ranked #4 of 30 in web application firewall software on Freedom251. It runs on Linux, macOS, Self-hosted, Windows. There is a free plan.

ModSecurity plans and pricing

All plans

ModSecurity Free Open-source WAF engine · runs as a module inside a web server modsecurity.org · 4 Oct 2026

Compared on web application firewall software

Free plan: Yes
Managed rule sets: No

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The record

Purpose: ModSecurity is an open-source, rule-based web application firewall that analyzes incoming traffic and helps block malicious requests before they reach an application.
Traffic inspection: The project describes ModSecurity as a cross-platform WAF module that provides visibility into HTTP(S) traffic and a rules language and API for implementing protections.
Web server integrations: ModSecurity can be installed as a module for Apache, Nginx, or IIS.
Rule sets: ModSecurity can run on its own or with the OWASP Core Rule Set, which the FAQ says provides broad coverage against common web attacks.
Usage scenarios: The project lists real-time application security monitoring and access control, full HTTP traffic logging, continuous passive security assessment, and web application hardening as usage scenarios.
Deployment: The FAQ says ModSecurity runs inside a web server rather than as a standalone appliance or proxy.
Supported operating systems: The FAQ lists Linux, Unix-like systems, Windows, and macOS when paired with a compatible web server.
Tuning: The installation guide recommends starting in detection-only mode, reviewing and tuning events, and then enabling blocking.
Performance: The FAQ says inspecting every incoming request can have a small performance impact and that tuning rules can help keep the site running smoothly.
Maintenance: The FAQ says ModSecurity is maintained by OWASP with support from a wider community of contributors.
Community: The project directs users to Slack and GitHub for community discussions and projects and says it welcomes contributors and developers.
Recent security fixes: A September 2026 security update digest describes fixes in ModSecurity 2.9.15 and libmodsecurity 3.0.17 for multiple reported issues.
Price from: Free

Where it ranks on Freedom251

Best Web Application Firewall Software in 2026#4 of 30

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Sources

modsecurity.org/faq/· checked 4 Oct 2026
modsecurity.org· checked 4 Oct 2026
modsecurity.org/installation/· checked 4 Oct 2026
modsecurity.org/20260928/security-update-digest-overvie· checked 4 Oct 2026