OWASP ZAP is a free, open-source web app security scanner and proxy for penetration testing. See 2026 features, use cases, and top alternatives.
OWASP ZAP is a dynamic application security testing tool: instead of reading source code or dependency manifests, it actively interacts with a running web application or API to find exploitable vulnerabilities the way an attacker would.
It works as an intercepting proxy, sitting between a browser or test client and the target application, which lets it both passively observe every request and response and actively send crafted, potentially malicious inputs to probe for weaknesses like injection flaws and cross-site scripting.
ZAP combines an automated scanner (both passive, which just observes traffic, and active, which sends attack payloads) with manual testing tools such as a traffic interceptor, request replay, and fuzzer, making it useful for both automated pipeline scans and hands-on penetration testing.
An automation framework lets teams script and schedule ZAP scans as part of CI/CD, while a marketplace of community-contributed add-ons extends the core tool with additional scan rules, authentication handlers, and reporting formats.
ZAP is entirely free and open source under the Apache License 2.0, with no paid tiers or feature gating; every capability, from active scanning to the automation framework, is available at no cost.
Since its core team joined Checkmarx in 2024 as ZAP by Checkmarx, the project has continued as an independently governed open-source effort backed by Checkmarx sponsorship rather than being converted into a commercial product, so pricing and licensing terms for end users have not changed.
OWASP ZAP is used to find security vulnerabilities in running web applications and APIs by actively and passively scanning traffic, similar to how a penetration tester would probe an application.
Yes, ZAP is completely free and open source under the Apache License 2.0, with no paid tiers.
ZAP left the OWASP Foundation in 2023 to join the Linux Foundation's Software Security Project, and in 2024 its core team joined Checkmarx, with the project now branded ZAP by Checkmarx while remaining free and open source.
ZAP is a dynamic application security testing tool that actively scans a running web application for vulnerabilities, while Dependency-Check is a software composition analysis tool that scans a project's dependencies for known vulnerable libraries.
ZAP was founded in 2010 by Simon Bennetts, forked from the Paros proxy originally developed by Chinotec Technologies.
Yes, ZAP includes an automation framework specifically designed to script and schedule scans as part of CI/CD workflows.
Common alternatives include Burp Suite, Acunetix, Invicti (formerly Netsparker), and Nikto.
Yes, ZAP can scan REST and SOAP APIs in addition to traditional web applications.