OWASP ZAP, which stands for Zed Attack Proxy, is a freely available, open-source tool for penetration testing, managed by the Open Web Application Security Project (OWASP). This tool is specifically crafted for evaluating web applications, offering both flexibility and extensibility to its users. At its foundation, ZAP operates as a "man-in-the-middle proxy," allowing it to sit between the user's browser and the web application, enabling the interception and inspection of communications exchanged between the two, with the option to modify the content before relaying it to its final destination. It can function independently as a standalone application or run as a daemon process in the background. ZAP caters to various experience levels, making it suitable for developers, novices in security testing, and seasoned security testing professionals alike. Furthermore, it is compatible with major operating systems and Docker, ensuring users are not restricted to a single platform. Users can also enhance their ZAP experience by accessing additional features through a variety of add-ons found in the ZAP Marketplace, which can be conveniently accessed directly within the ZAP client. The continuous updates and community support further contribute to its robustness as a security testing solution.