A web application penetration tester, also known as a web application security tester, is a cybersecurity professional who specializes in identifying and testing vulnerabilities in web applications. Web applications are software programs that are accessed via a web browser and that run on a web server. They are commonly used to provide online services such as e-commerce, banking, and social media.

Web application penetration testers use a variety of tools and techniques to identify and exploit vulnerabilities in web applications. This may involve using automated scanners to identify common vulnerabilities, such as SQL injection and cross-site scripting (XSS), or manually testing the application to identify more complex or subtle vulnerabilities.

Web application penetration testers work to identify vulnerabilities before attackers can exploit them, and they provide recommendations for how to fix those vulnerabilities. They may also work with developers to help them build more secure web applications.

Web application penetration testers typically have a strong background in computer science or a related field, and they may hold relevant certifications such as the Certified Ethical Hacker (CEH) or the Offensive Security Certified Professional (OSCP). They may work in a variety of settings, including in-house security teams, consulting firms, or as freelance contractors.