
Open-source web app scanner
Free

ZAP (Zed Attack Proxy) is the world’s most widely used open-source web application security scanner. It acts as a man-in-the-middle proxy, allowing developers and security professionals to intercept, inspect, and modify traffic between a browser and a web application. Unlike commercial alternatives like Burp Suite Professional, ZAP is entirely free and community-driven, offering a robust API for CI/CD integration. It excels in automated security testing, vulnerability scanning, and manual penetration testing, providing a comprehensive suite of tools to identify OWASP Top 10 risks, SQL injection, and XSS vulnerabilities in real-time.
ZAP provides a powerful active scanner that crawls applications to identify vulnerabilities like SQL injection, Cross-Site Scripting (XSS), and insecure headers. By automating the attack surface analysis, it allows developers to catch critical security flaws during the development phase, significantly reducing the cost of remediation compared to finding these issues in production environments.
The ZAP Automation Framework allows security testing to be embedded directly into DevOps pipelines. By using YAML-based configuration files, teams can trigger automated scans on every pull request. This ensures that security regressions are caught early, providing a measurable security gate that prevents vulnerable code from reaching production environments.
ZAP features a robust marketplace that allows users to extend functionality through community-contributed add-ons. Whether you need specialized support for modern JavaScript frameworks, custom authentication scripts, or integration with external vulnerability management platforms, the modular architecture ensures ZAP evolves alongside the rapidly changing web technology landscape.
As a man-in-the-middle proxy, ZAP allows for granular inspection and manipulation of HTTP requests and responses. This is essential for manual penetration testing, enabling security researchers to bypass client-side validation, modify session tokens, or fuzz specific input fields to discover edge-case vulnerabilities that automated scanners might miss.
ZAP supports custom scripting in languages like JavaScript, Python, and Zest. This allows users to automate complex authentication flows, such as multi-factor authentication (MFA) or custom token-based headers, which are often blockers for standard automated scanners. This flexibility makes ZAP highly effective for testing modern, complex web applications.
Security engineers integrate ZAP into Jenkins or GitHub Actions to run automated scans on every build. This ensures that new code commits do not introduce common vulnerabilities like XSS or SQLi, providing immediate feedback to developers and maintaining a secure deployment velocity.
Security consultants use ZAP as their primary proxy to intercept traffic, analyze API responses, and manually fuzz endpoints. This allows them to identify complex business logic flaws that automated tools cannot detect, resulting in a more thorough security assessment.
Researchers use ZAP to map out the attack surface of web applications. By utilizing the spidering and forced browsing features, they can discover hidden directories and undocumented API endpoints, helping them build a comprehensive map of the target's infrastructure.
Need a reliable, scriptable tool to automate security testing within CI/CD pipelines to ensure compliance and reduce the risk of production vulnerabilities.
Require an easy-to-use tool to identify and fix security flaws in their code during the development phase, before deployment to production.
Need a powerful, customizable proxy to intercept and manipulate traffic for deep-dive security assessments and vulnerability discovery.
100% free and open-source. Distributed under the Apache License 2.0. No paid tiers or hidden costs; fully community-maintained.