Open Source Web Application FirewallModSecurity is an open source, cross-platform web application firewall (WAF) module. Known as the “Swiss Army Knife” of WAFs, it enables web application defenders to gain visibility into HTTP(S) traffic and provides a power rules language and API to implement advanced protections. Get latest v2: 2.9.8 Get latest v3: 3.0.13 The most widespread open source WAFUsed