Web Firewalls Measured on False Positives and Latency
OWASP Top 10 attacks hit thousands of apps daily. We compare 6 web application firewalls on rule sets, false positive rates, and latency impact.
At MG Software, we recommend Cloudflare WAF for most clients. The combination of the world's largest network, a free tier, and simple configuration makes it the best choice for both small and large web applications. For AWS-native environments, AWS WAF is the logical alternative.
A Web Application Firewall (WAF) is your first line of defense against common web attacks like SQL injection, cross-site scripting (XSS), request smuggling, and server-side request forgery (SSRF). In 2026 web applications face more threats than ever before: automated botnets continuously scan for vulnerabilities, API endpoints are exploited for credential stuffing, and zero-day exploits are weaponized within hours of disclosure. A WAF filters all HTTP and HTTPS traffic at the application layer (layer 7 of the OSI model) and blocks suspicious requests before they reach your server, providing an essential safety net on top of secure code and regular penetration testing. When choosing a WAF solution, key factors include OWASP Top 10 coverage, protection against API abuse and automated bots, latency impact on end users, and the flexibility to write custom rules without locking yourself into a single cloud provider. In this comparison we analyze six WAF solutions that we have tested and deployed in real-world client projects.
How did we select these tools?
We tested each WAF against the OWASP Top 10 attack vectors using real traffic replays, measured false-positive rates on production-like workloads, and evaluated configuration complexity, pricing transparency, and integration with CDN and cloud providers.
How do we evaluate these tools?
- Protection against OWASP Top 10 and zero-day vulnerabilities, including recent attack vectors like SSRF and prototype pollution
- Performance impact on latency and traffic throughput, measured with production-like workloads on European servers
- Configuration ease and quality of managed rulesets, plus the ability to quickly add custom rules for application-specific logic
- Value for money and availability of a free tier or affordable entry-level plan for smaller projects and startups
- Deployment flexibility: managed cloud WAF, self-hosted, or hybrid setup with support for multi-cloud environments
- API protection and bot detection, including per-endpoint rate limiting, credential-stuffing prevention, and automated traffic fingerprinting
1. Cloudflare WAF
WAF from the world's largest CDN network with more than 330 data centers across 120 countries. Cloudflare provides managed rulesets for OWASP Top 10, bot management via Bot Fight Mode, and DDoS mitigation at both network and application level. The free plan already includes basic WAF rules and unlimited DDoS protection. Pro plans start at $20/month and add advanced rulesets, image optimization, and Web Analytics. The Business plan ($200/month) unlocks custom WAF rules and priority support.
Pros
- +Largest network (330+ data centers) for minimal latency worldwide
- +Free tier with basic DDoS protection and five custom WAF rules included
- +Managed rulesets for OWASP Top 10 and emerging threats are automatically updated
- +Simple configuration via dashboard, Terraform, or API with ruleset version control
- +Bot Fight Mode and Super Bot Fight Mode for automated detection of malicious bot traffic
Cons
- -Advanced WAF rules and custom rulesets require the Pro or Business plan
- -Custom rules are limited to five on the free plan and twenty on Pro
- -False positives with aggressive managed rulesets require manual exceptions per rule ID
- -Full API protection (schema validation, sequence detection) is only available on Enterprise
2. AWS WAF
Native WAF service from Amazon Web Services that seamlessly integrates with CloudFront, Application Load Balancer, API Gateway, and AppSync. AWS WAF offers flexible rule configuration based on IP, geo, rate, and regex patterns. Hundreds of pre-built rule groups from vendors like Fortinet and F5 are available through AWS Managed Rules and the Marketplace. Pricing follows a pay-per-use model: $5 per web ACL per month, $1 per rule group, and $0.60 per million requests. Real-time monitoring runs through CloudWatch and AWS Firewall Manager.
Pros
- +Native integration with CloudFront, ALB, API Gateway, and AppSync without additional proxying
- +Flexible rule engine with rate limiting, geo-blocking, and regex matching on headers and body
- +Hundreds of managed rule groups available via AWS and third parties in the AWS Marketplace
- +Pay-per-use pricing with no upfront commitments, ideal for variable traffic patterns
- +Centralized management across multiple accounts via AWS Firewall Manager for enterprise setups
Cons
- -More complex initial configuration compared to Cloudflare, requiring knowledge of IAM and CloudFormation
- -Vendor lock-in within the AWS ecosystem, making migration to other cloud providers difficult
- -No free tier: even with low traffic you pay a minimum of $5/month per web ACL
- -Logging to S3 or Kinesis requires separate configuration and incurs additional storage costs
3. Sucuri
WAF and security platform specializing in WordPress, Joomla, Drupal, and other CMS environments. Sucuri provides a cloud-based WAF with virtual patching, blocking known vulnerabilities before a plugin update is even available. The platform also includes website monitoring, malware scanning, and a professional cleanup service in case of infection. Pricing starts at $199.99/year for the Basic plan (one site) and goes up to $499.99/year for the Business plan with faster response times and advanced DDoS protection.
Pros
- +Specialist in WordPress and CMS security with virtual patches for thousands of known exploits
- +Includes malware scanning, blacklist monitoring, and professional cleanup in case of infection
- +Virtual patching blocks attacks on known CMS vulnerabilities without requiring code changes
- +Website monitoring, uptime checks, and SSL certificate monitoring included in every plan
- +Simple DNS redirect setup with no server-side installation required
Cons
- -Less suitable for custom web applications, SPAs, and API-only backends
- -More limited custom rule configuration options than Cloudflare or AWS WAF
- -Multi-site protection requires separate licenses, which gets expensive with many sites
- -CDN network is smaller than Cloudflare, which can result in higher latency in Asia-Pacific regions
4. ModSecurity
The most widely used open-source WAF engine that runs as a module for Apache, Nginx, and IIS. ModSecurity provides full control over rulesets and serves as the backbone of many commercial WAF products. The OWASP Core Rule Set (CRS) v4 is the standard ruleset and covers the full OWASP Top 10 plus thousands of additional patterns. Version 3.x (libmodsecurity) was rewritten as a standalone C library for better performance and easier integration. ModSecurity is entirely free with no licensing costs but requires self-hosting and maintenance.
Pros
- +Fully open-source and free to use with no licensing or subscription costs
- +OWASP Core Rule Set (CRS) v4 as a proven and actively maintained ruleset
- +Maximum control over rules, logging, and response actions via SecRule syntax
- +No vendor lock-in: runs on any server with Apache, Nginx, or IIS
- +Large community and extensive documentation for troubleshooting and custom rule creation
Cons
- -Requires deep knowledge of regular expressions and SecRule syntax for correct configuration
- -Operational overhead for rule updates, performance tuning, and log analysis
- -No managed dashboard, all configuration runs through text files on the server
- -No built-in bot detection or API-specific protection without additional tooling
5. Fastly Next-Gen WAF (Signal Sciences)
Next-generation WAF from Fastly, born from the acquisition of Signal Sciences in 2020. This WAF uses SmartParse technology to detect request anomalies without traditional regex rules, resulting in significantly lower false-positive rates than classic WAF solutions. The agent-based architecture works on edge, cloud, and on-premises, protecting both web applications and APIs. Pricing is enterprise-oriented and not publicly listed, but typically starts at several thousand euros per month.
Pros
- +Low false-positive rate thanks to SmartParse technology that understands context rather than just patterns
- +Real-time threat dashboard and configurable alerting via webhooks, Slack, and PagerDuty
- +Works on edge (Fastly CDN), cloud, and on-premises via a lightweight agent
- +API protection, account takeover prevention, and per-endpoint rate limiting included
- +No rule tuning needed for most deployments, significantly reducing operational burden
Cons
- -Enterprise pricing, not suitable or affordable for small projects and startups
- -Agent installation required on every server, container, or edge node in your infrastructure
- -Less intuitive initial configuration and onboarding compared to Cloudflare
- -Limited visibility into the exact workings of the detection engine due to proprietary technology
6. Imperva WAF
Enterprise-grade cloud WAF from Imperva (part of Thales Group) that combines DDoS protection, advanced bot management, and API security into an integrated platform. Imperva protects over 8,000 organizations globally and excels in compliance support for PCI DSS, HIPAA, and SOC 2. The platform provides automatic rule updates from the Imperva Threat Research Center and supports both cloud-only and hybrid deployments. Pricing is custom and typically starts from $500/month for the FlexProtect plan.
Pros
- +Integrated DDoS protection at network and application level with 9 Tbps of mitigation capacity
- +Advanced bot management with device fingerprinting, CAPTCHA challenges, and behavioral analysis
- +Extensive compliance support with pre-configured rulesets for PCI DSS, HIPAA, and SOC 2
- +API security with automatic schema discovery, rate limiting, and payload inspection
- +Threat Research Center delivers continuous rule updates based on proprietary threat intelligence
Cons
- -High entry price and complex licensing structure with multiple add-on modules
- -Onboarding and initial configuration often require assistance from Imperva Professional Services
- -Dashboard can feel overwhelming due to the large number of features and reporting options
- -Less suitable for small to mid-size projects due to enterprise-oriented pricing and contracts
Which tool does MG Software recommend?
At MG Software, we recommend Cloudflare WAF for most clients. The combination of the world's largest network, a free tier, and simple configuration makes it the best choice for both small and large web applications. For AWS-native environments, AWS WAF is the logical alternative.
How MG Software can help
As a web development agency with years of experience in application security, MG Software helps you select the WAF solution that fits your infrastructure, budget, and compliance requirements. We perform a security audit to map your specific risk profile and recommend the best-fitting WAF based on our findings. After selection, we fully configure the WAF, including writing custom rules for your specific application logic and setting up exceptions to minimize false positives. We also set up monitoring and alerting through your existing toolchain so your team is immediately informed of suspicious activity. Additionally, we provide ongoing maintenance, regular rule updates, and quarterly reviews of your WAF configuration to ensure your protection stays current as new threats emerge.
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