Overview
HAProxy is the world's most widely used open source software load balancer and application delivery controller, powering high-traffic websites and APIs for companies including Airbnb, Reddit, Imgur, GitHub, and Roblox. HAProxy Technologies, the company behind the project, offers an enterprise WAF as part of HAProxy Enterprise that takes a fundamentally different approach to web application security.
Unlike traditional WAFs that rely on regex-based attack signatures and static rule lists, the HAProxy Enterprise WAF uses an Intelligent WAF Engine powered by machine learning. HAProxy's data science team trains security models using threat intelligence data from over 60 billion daily requests processed on HAProxy Edge. This approach detects emerging and zero-day threats without requiring manual rule creation or signature updates.
The WAF runs in the same process as HAProxy itself, which means enabling it adds virtually no latency or CPU overhead. At HAProxyConf 2025, Roblox reported that activating the WAF caused negligible CPU increase while catching significant volumes of malicious traffic. Open source benchmarks show a 99.8% true-positive rate and 97.1% true-negative rate, giving a balanced accuracy of 98.5%, well above the industry average of around 90%.
HAProxy Enterprise WAF also includes an optional OWASP Core Rule Set (CRS) compatibility mode. This runs CRS rules through the Intelligent WAF Engine rather than traditional regex processing, resulting in drastically lower latency and fewer false positives compared to standard CRS deployments.
The WAF is one component of HAProxy's broader security platform. HAProxy Enterprise also includes bot management, global rate limiting, a CAPTCHA module, and DDoS protection. HAProxy Fusion provides a centralized control plane for managing WAF policies across multi-cluster, multi-cloud deployments. HAProxy Edge offers the same WAF as a fully managed cloud service with a global delivery network.
It is important to understand that HAProxy Community (the free open source version) does not include the WAF. The WAF requires HAProxy Enterprise, which is a commercial product with custom pricing. HAProxy Community provides basic ACL-based traffic filtering and rate limiting, but not application-layer threat detection.
Ratings Breakdown
Key Features
Intelligent WAF Engine
Machine learning-powered threat detection trained on 60+ billion daily requests. Detects zero-day and polymorphic attacks without relying on static signatures. 98.5% balanced accuracy in open source benchmarks.
OWASP CRS Compatibility
Optional mode that runs OWASP Core Rule Set rules through the Intelligent WAF Engine, dramatically reducing latency and false positive rates compared to traditional CRS processing.
WAF Profiles
Customizable security profiles per application, allowing fine-tuned policies based on each app's unique traffic patterns. Minimizes false positives and alert fatigue for diverse application portfolios.
Bot Management
Proprietary bot detection module with 100% local processing for low latency. Identifies and manages automated traffic using fingerprinting and behavioral analysis.
Global Rate Limiting
Dynamic, cluster-wide rate limiting powered by the Global Profiling Engine. Tracks and enforces rate limits in real-time across distributed deployments.
HAProxy Fusion Control Plane
Centralized management, monitoring, and automation of WAF policies across multi-cluster, multi-cloud, and multi-team deployments from a single dashboard.
DDoS Protection
Full-spectrum DDoS mitigation via HAProxy Edge, protecting against volumetric, protocol, and application-layer attacks.
In-Process Architecture
WAF runs in the same process as HAProxy, adding virtually zero latency and CPU overhead. No separate WAF appliance or proxy hop required.
Threat Intelligence
Real-time threat intelligence from HAProxy Edge's global network, continuously updating the ML models that power the WAF engine.
Pros & Cons
Pros
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Exceptional accuracy
98.5% balanced accuracy (99.8% true-positive, 97.1% true-negative) significantly outperforms the industry average of around 90%. Fewer missed attacks and fewer false alarms.
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Near-zero latency
WAF runs in-process with HAProxy, adding sub-millisecond latency. Roblox confirmed negligible CPU impact when activating the WAF on their high-traffic infrastructure.
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No rule maintenance
ML-powered detection eliminates the need to manually write, tune, and update WAF rules. The Intelligent WAF Engine adapts to new threats automatically.
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Battle-tested at scale
HAProxy itself is proven at massive scale (Airbnb, Reddit, GitHub, Roblox). The WAF inherits this performance heritage and is used by some of the world's largest platforms.
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Integrated platform
WAF is part of a complete application delivery platform including load balancing, bot management, rate limiting, and DDoS protection. No bolting on separate products.
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Flexible deployment
On-premises, cloud, Kubernetes, virtual appliance, or fully managed cloud service. Same WAF engine across all deployment models.
Cons
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No free WAF tier
The WAF is only available in HAProxy Enterprise (paid). HAProxy Community, while free, only provides basic ACL filtering and rate limiting without application-layer threat detection.
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Custom pricing only
No published pricing. Requires contacting sales for a quote, which can be a barrier for smaller teams evaluating options.
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Proprietary engine
The Intelligent WAF Engine is proprietary and closed-source. Organizations cannot inspect or audit the ML models powering their security decisions.
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Community edition limitations
Teams using HAProxy Community who need WAF protection must either upgrade to Enterprise or deploy a separate WAF solution (like ModSecurity or Coraza) alongside HAProxy.
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Smaller WAF ecosystem
HAProxy's WAF-specific community is smaller than Cloudflare's or ModSecurity's. Fewer third-party tutorials, integrations, and community-contributed rules.
Pricing
Pricing model: Custom pricing (contact sales)
HAProxy Community
Open source load balancer without WAF. Includes ACL-based filtering, rate limiting, SSL termination, and HTTP routing. No enterprise WAF, bot management, or support.
- TCP and HTTP load balancing
- SSL/TLS termination
- ACL-based traffic filtering
- Basic rate limiting
- HTTP caching and compression
- DNS-based service discovery
- Lua scripting
- Data Plane API
HAProxy Enterprise
Enterprise load balancer with full WAF, bot management, global rate limiting, and 24/7 support. Includes HAProxy Fusion control plane for multi-cluster management.
- Everything in Community
- Intelligent WAF Engine (ML-powered)
- OWASP CRS compatibility mode
- Bot Management Module
- Global Rate Limiting
- CAPTCHA module (reCAPTCHA, hCaptcha)
- Native SSO (Active Directory, SAML)
- HAProxy Fusion control plane
- 24/7/365 expert support
- Curated packages and early access
HAProxy Edge
Fully managed cloud service with global delivery network. Same WAF engine as Enterprise with added DDoS protection, CDN, and managed security operations.
- Everything in Enterprise
- Global application delivery network
- Full-spectrum DDoS protection
- Managed WAF operations
- Content delivery and acceleration
- Comprehensive observability suite
- Threat intelligence feeds
HAProxy ALOHA
Dedicated hardware or virtual load balancer appliance based on HAProxy Enterprise. For organizations requiring turnkey, high-performance routing with WAF included.
- Hardware or virtual appliance
- HAProxy Enterprise included
- WAF and security features
- Simplified deployment
Our Verdict
HAProxy Enterprise WAF is a compelling choice for organizations that already use HAProxy for load balancing and want to add WAF protection without introducing another proxy layer or latency. The ML-powered Intelligent WAF Engine is genuinely innovative, delivering accuracy numbers that most signature-based WAFs cannot match.
The standout advantage is performance. Running the WAF in-process means you get application-layer security at network-layer speeds. For high-traffic APIs and real-time applications where every millisecond matters, this is a significant differentiator.
The main drawback is cost and accessibility. There is no free WAF tier, no published pricing, and the proprietary engine means you are trusting HAProxy's ML models rather than inspecting rules yourself. Organizations running HAProxy Community who need WAF protection face a choice: pay for Enterprise, or bolt on a separate WAF like ModSecurity or Coraza.
For enterprise teams already invested in the HAProxy ecosystem, the WAF is an excellent addition. For everyone else, the lack of a free tier and transparent pricing makes it harder to evaluate against alternatives like Cloudflare (free tier) or Coraza (open source).
CVE Coverage
HAProxy Enterprise WAF can detect and block attacks matching 87K+ known CVEs based on its supported rule sets.
Coverage by Attack Type
Latest Blockable CVEs
| CVE | Severity |
|---|---|
| CVE-2026-4510 | MEDIUM |
| CVE-2026-4161 | MEDIUM |
| CVE-2026-4087 | MEDIUM |
| CVE-2026-4086 | MEDIUM |
| CVE-2026-4084 | MEDIUM |
| CVE-2026-4077 | MEDIUM |
| CVE-2026-4072 | MEDIUM |
| CVE-2026-4069 | MEDIUM |
| CVE-2026-4067 | MEDIUM |
| CVE-2026-4022 | MEDIUM |
Frequently Asked Questions
Does HAProxy Community include a WAF?
No. HAProxy Community is an open source load balancer that provides ACL-based traffic filtering and basic rate limiting, but does not include application-layer WAF protection. The WAF is exclusive to HAProxy Enterprise. If you need WAF protection with HAProxy Community, you can deploy a separate WAF like ModSecurity or Coraza alongside it.
How does HAProxy Enterprise WAF compare to ModSecurity?
They take fundamentally different approaches. ModSecurity uses regex-based pattern matching with the OWASP Core Rule Set, which requires ongoing rule tuning. HAProxy Enterprise WAF uses machine learning-powered detection that adapts to new threats automatically. HAProxy claims 98.5% balanced accuracy vs. the industry average of around 90%. However, ModSecurity is free and open source, while HAProxy Enterprise WAF requires a commercial license.
What is HAProxy Edge?
HAProxy Edge is the fully managed cloud version of HAProxy's platform. It includes the same WAF engine as HAProxy Enterprise, plus a global delivery network, DDoS protection, bot management, and managed security operations. Think of it as HAProxy Enterprise delivered as a managed service, similar to how Cloudflare delivers its WAF through its CDN.
Can I try HAProxy Enterprise WAF for free?
HAProxy offers a free trial of HAProxy Enterprise that includes the WAF. Visit haproxy.com/hapee-trial to request access. There is no permanently free tier for the WAF.
How much does HAProxy Enterprise WAF cost?
HAProxy Enterprise uses custom pricing based on your deployment scale and requirements. You need to contact their sales team for a quote. Pricing is not publicly listed, which is common for enterprise-grade application delivery products in this category.
What is the Intelligent WAF Engine?
The Intelligent WAF Engine is HAProxy's proprietary, patent-pending threat detection system. Instead of matching traffic against regex-based attack signatures, it uses machine learning models trained on threat intelligence data from 60+ billion daily requests. This enables it to detect zero-day attacks and polymorphic threats that signature-based WAFs miss, while producing fewer false positives.
Does HAProxy Enterprise WAF support OWASP CRS rules?
Yes. HAProxy Enterprise WAF includes an optional OWASP CRS compatibility mode. It processes CRS rules through the Intelligent WAF Engine rather than traditional regex evaluation, which HAProxy says results in dramatically lower latency and fewer false positives compared to running CRS on ModSecurity.
Who uses HAProxy Enterprise WAF?
HAProxy Enterprise is used by major platforms including Roblox, which processes millions of requests per second through hundreds of HAProxy instances. Other notable HAProxy users include Airbnb, Reddit, GitHub, Stack Overflow, and Imgur, though not all may use the WAF component specifically.
Ready to try HAProxy Enterprise WAF?
Visit the website to learn more or request a demo.