Cloud · head to head
HAProxy vs OWASP ZAP
OWASP ZAP
Cybersecurity
Free, open-source web application scanner and intercepting proxy, now governed by the Software Security Project.
- From
- Free
- Rated
- -
The short version
- Each has a real cost: HAProxy configuration syntax is dense and unforgiving, with a steep initial learning curve; OWASP ZAP authenticated scanning of modern single-page applications is the hard part and ZAP makes you build it by hand: session handling, token refresh and login scripts are configured per application, and a misconfigured session means the scanner logs itself out and reports a clean result for pages it never reached.
- They diverge on capability: HAProxy covers High throughput, OWASP ZAP covers Intercepting proxy.
- Prices and features above were last checked on 30 August 2026.
Where they differ
Only the attributes on which HAProxy and OWASP ZAP actually diverge.
Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated).
What each one covers
Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.
Only in HAProxy
- High throughput
- Layer 4 and 7
- Health checking
- Rate limiting and ACLs
Only in OWASP ZAP
- Intercepting proxy
- Passive scanner
- Active scanner
- AJAX spider
- Automation Framework
- Headless daemon and REST API
- Docker images
- Add-on marketplace
What people use each for
The jobs each tool is most often brought in to do.
HAProxy
- Load balancing at traffic levels where proxy efficiency shows up in the hardware billnot OWASP ZAP
- Precise traffic control — rate limits, sticky sessions, complex routing rulesnot OWASP ZAP
- TCP load balancing for databases and non-HTTP servicesnot OWASP ZAP
OWASP ZAP
- Adding a baseline security scan to every application's pipeline where per-target commercial licensing would limit coverage to a handfulnot HAProxy
- Manual penetration testing that needs an intercepting proxy, request replay and fuzzing without a paid licence per testernot HAProxy
- Teaching developers what an attack against their own endpoint looks like, using a tool they can install themselvesnot HAProxy
- Pre-release regression scanning of an internal application that would never justify a commercial DAST subscriptionnot HAProxy
Where each one falls short
Documented limitations, not opinions. Every one is a constraint you would hit in normal use.
HAProxy
- Configuration syntax is dense and unforgiving, with a steep initial learning curve
- No automatic certificate management, unlike newer servers that treat it as default behaviour
- The built-in stats page is basic, so real observability needs exporters and dashboards
- A dedicated load balancer is more machinery than small deployments need
OWASP ZAP
- Authenticated scanning of modern single-page applications is the hard part and ZAP makes you build it by hand: session handling, token refresh and login scripts are configured per application, and a misconfigured session means the scanner logs itself out and reports a clean result for pages it never reached.
- There is no support contract in the product, so when a scan breaks the day before a release the escalation path is a GitHub issue and a community chat, which is not an answer that satisfies a delivery manager or an auditor who wants a named responsible party.
- Active scanning sends genuine attack traffic, so it can create records, trigger emails, exhaust rate limits or destabilise a fragile environment, and pointing it at production without prior agreement produces an incident rather than a test result.
- Output needs triage: passive rules generate large volumes of low-severity informational findings about headers and cookie flags that bury the few results that matter, and a team without someone tuning the rule set stops reading the report within a few sprints.
- As a dynamic scanner it can only test what it can reach, so authorisation flaws between accounts, business logic abuse and anything behind an undiscovered endpoint go unreported, and a passing ZAP scan is evidence of nothing more than the absence of the classes of bug it looks for.
Pricing, plan by plan
HAProxy
Free- HAProxyFree
- Full functionality
- No usage limits
- Community support
OWASP ZAP
Free- Free & Open SourceFree
- Full functionality
- Active & passive scanning
- Spider
Which should you pick?
Choose HAProxy if
- You need high throughput.
- You want to start without paying.
- You work on Linux, Docker, Kubernetes, Self-hosted.
- You also want layer 4 and 7.
Choose OWASP ZAP if
- You need intercepting proxy.
- You want to start without paying.
- You work on Desktop, Cli, Api.
- You also want passive scanner.
Questions people ask
- Is HAProxy or OWASP ZAP better?
- Neither clearly leads. HAProxy starts at Free and OWASP ZAP at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
- Which is cheaper, HAProxy or OWASP ZAP?
- HAProxy starts at Free and OWASP ZAP at Free.
- Does HAProxy or OWASP ZAP run on more platforms?
- HAProxy runs on Linux, Docker, Kubernetes, Self-hosted. OWASP ZAP runs on Desktop, Cli, Api.
- Can I use HAProxy for free?
- Both have a free tier, so you can try either at no cost before committing.
- What is HAProxy best used for?
- HAProxy is most often used for load balancing at traffic levels where proxy efficiency shows up in the hardware bill, precise traffic control — rate limits, sticky sessions, complex routing rules, tcp load balancing for databases and non-http services. Of those, load balancing at traffic levels where proxy efficiency shows up in the hardware bill and precise traffic control — rate limits, sticky sessions, complex routing rules are not what OWASP ZAP is typically brought in for.
- What can HAProxy do that OWASP ZAP cannot?
- HAProxy covers High throughput, Layer 4 and 7, Health checking, Rate limiting and ACLs. OWASP ZAP covers Intercepting proxy, Passive scanner, Active scanner, AJAX spider.
Answered from the vendors’ own pages
HAProxy: Is HAProxy free?
Yes, the community version is open source. HAProxy Technologies sells HAProxy Enterprise separately.
OWASP ZAP: Is it still called OWASP ZAP?
The project left OWASP in August 2024 and is now governed by the Software Security Project, with core development sponsored by Checkmarx. The tool is now just ZAP, though most existing documentation, courses and search results still use the OWASP name.
HAProxy: HAProxy or Nginx?
HAProxy is a specialist load balancer with deeper balancing and health-check features. Nginx also serves static content and is more approachable, which is why it is more common as a general web server.
OWASP ZAP: Is it free for commercial use?
Yes. It is Apache 2.0 licensed, with no per-application, per-scan or per-user cost, and it can be used and modified commercially without a licence agreement.
HAProxy: Does HAProxy handle TLS certificates automatically?
No. Certificate issuance and renewal are external, unlike Caddy where it is automatic.
OWASP ZAP: Can it replace a penetration test?
No. It automates checks for known vulnerability classes against endpoints it can reach. It does not reason about business logic, chain findings into an attack, or test authorisation between accounts, which is most of what a tester actually does.
OWASP ZAP: Does it run in CI?
Yes, through the official Docker images and the Automation Framework, which defines scan jobs in YAML so configuration lives in the repository. A baseline passive scan is the usual starting point because it is fast and non-intrusive.
OWASP ZAP: How does it compare to Burp Suite?
Burp Suite Professional is the more polished manual testing tool and has a stronger scanner and extension ecosystem, but it is licensed per tester and Burp Suite Enterprise per target. ZAP is the better fit where cost per target is the binding constraint; many teams use both.
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