NAXSI vs Shield Security

NAXSI

Model: Free (Open Source, GPLv3)

Free Tier Available View full pricing →

Shield Security

Model: Freemium (Free tier + annual ShieldPRO license)

Free Tier Available View full pricing →

NAXSI

• Scoring-Based Detection

  Assigns scores to suspicious patterns in requests. Blocks when the cumulative score exceeds a threshold, rather than relying on exact signature matches.

• Learning Mode

  Monitors traffic and automatically generates whitelist rules for legitimate application behavior, reducing manual tuning effort during initial deployment.

• Virtual Patching

  Apply custom rules to block specific vulnerabilities without modifying application code. Rules target raw requests or specific fields like headers, args, and body.

• Deny-by-Default

  Operates like a DROP firewall. Common attack characters and patterns are blocked unless explicitly whitelisted for the target application.

• Lightweight Footprint

  Written in C with only libpcre as a dependency. Adds minimal overhead to NGINX request processing.

• Dynamic Module Support

  Can be compiled as a dynamic NGINX module, allowing it to be loaded without recompiling NGINX from source.

Shield Security

• SilentCAPTCHA

  Proprietary invisible bot detection that identifies automated threats without showing challenges to visitors.

• AntiBot Detection Engine

  Behavioral analysis engine that identifies and blocks malicious bots based on activity patterns.

• Automatic IP Blocking

  Builds reputation scores for visitors and automatically blocks IPs that exhibit malicious behavior patterns.

• Firewall Rules

  Protection against SQL injection, XSS, directory traversal, and other common WordPress attack vectors.

• Activity Log

  Comprehensive log of all security events, user actions, and blocked threats for auditing.

• Traffic Rate Limiting

  Controls request rates to prevent brute force attacks and resource exhaustion (ShieldPRO feature).