Burp Suite vs OWASP ZAP: the proxy that pays its rent.

Burp Suite Professional is the industry default. OWASP ZAP is the free, community-maintained alternative. The pitch for ZAP is "everything Burp does, for nothing". The pitch is mostly true and the gaps that remain are the entire reason consultancies still buy Burp licences.

The short answer

• Manual interactive testing: Burp wins by a margin that everyone underestimates.
• Free / open source / CI integration: ZAP wins by default — there is no Burp equivalent that costs nothing.
• Authenticated scanning of a SPA: ZAP is closer to "works out of the box".
• Extensions: Burp's BApp Store is deeper; ZAP's add-ons are catching up.

Manual testing: Burp's home turf

The Burp Repeater is the killer app. Send a request, edit any byte, hit Go, see the response. ZAP has the same feature (Requester) but the UX is a half-step behind: less keyboard-driven, less forgiving of malformed input. On a hard target you might Repeater five hundred requests in an afternoon. Half a second per request adds up.

Intruder (Burp) and Fuzzer (ZAP) both do parameter fuzzing. Intruder's payload sets and grep extraction are richer. ZAP's Fuzzer is competent but you will reach for an external tool — ffuf, wfuzz — sooner.

Headless / CI: ZAP's home turf

ZAP ships a Docker image and an automation framework explicitly designed for CI. The zap-baseline.py wrapper is a one-liner that gives you a security gate in any pipeline.

docker run -t zaproxy/zap-stable zap-baseline.py \
  -t https://staging.example.com \
  -r baseline-report.html

Burp Enterprise can do this — it costs from $5K per node per year. For most teams that question answers itself.

Extension surface

The numbers tell a story but mask another: in our lab the five extensions we used most often (Autorize, Active Scan++, JWT Editor, Hackvertor, Param Miner) are all Burp-only and all critical to specific workflows.

Active scanning: where they tie, where they don't

Run both scanners against the broken-app suite (DVWA, Juice Shop, WebGoat, NodeGoat, BWA, plus three internal benchmarks). Both find the easy stuff — reflected XSS, SQL injection on numeric parameters, basic IDOR. Where they diverge:

• Auth-aware blind injection: Burp catches a noticeable share that ZAP misses, primarily because of richer payload variation in Intruder.
• Modern SPAs (React/Vue) under authentication: ZAP's HUD makes session handling easier; Burp's macro recorder requires more setup but is more powerful once set.
• WebSocket-heavy apps: Burp's WS support is more mature.
• GraphQL: roughly a tie with the right extensions on each.

The "free" caveat

Burp has a Community Edition. It is severely throttled — no Intruder rate, no saved sessions, no extensions. It exists to give you a flavour, not to do real work. The fork in the road is real: ZAP all the way down, or Burp Pro and the licence cost.

The recommendation

If you are a security engineer at a company that does security as a function, the cost of Burp Pro is below the cost of the time it saves in a quarter. Buy it.

If you are a developer doing security-aware work, a contractor on a budget, a small shop, or anyone who needs to put a scan in a pipeline — ZAP is the right tool, and the gap to Burp is small enough that you will rarely notice it.

If you are training new testers, start them on ZAP. The free price tag means they can install it on a personal laptop without paperwork, and the UI metaphors transfer cleanly to Burp later.