Understanding cross-site scripting (XSS) is important for developers and security teams. This article highlights the most popular vulnerable websites and platforms where specialists can practice such attacks in a controlled environment, improving secure coding and penetration testing skills.
Why Cross-Site Scripting Testing Matters
XSS allows malicious code to be executed in a target’s browser, allowing attackers to steal sensitive data, hijack sessions, and launch phishing attacks. These vulnerabilities often arise from insufficient validation of user-provided input and content. Cross-site scripting testing improves teams’ ability to detect these flaws early on. Also using a vulnerability scanner can help find these issues much faster in both client-side and server-side code.
To help improve skills or test tools, this article has curated a collection of free platforms designed to practice cross-site scripting and other common web attacks.
Vulnerable Sites for XSS Testing
The resources below fall into three main categories: cross-site scripting-related tasks, security training platforms, and vulnerable test environments.
1. OWASP Juice Shop
This open-source web application covers all types of cross-site scripting, from basic injecting to advanced DOM-based attacks in a controlled environment. The platform runs on Node.js and supports penetration testing with both client-side and server-side vulnerabilities. It also allows users to analyze how improperly sanitized source code can pose risks.
2. HackThisSite
This platform offers a variety of web security exercises and real-world hacking simulations, where identifying and exploiting cross-site scripting vulnerabilities is a key objective. Many of the exercises involve bypassing JavaScript-based data entry restrictions, evading validation filters, and injecting scripts into HTML code. The site encourages collaborative learning with discussion forums where users can share ideas and techniques (without providing direct solutions). It also highlights social engineering tactics that use XSS exploits.
3. Damn Vulnerable Web Application (DVWA)
This is a vulnerable PHP-based website that provides an ideal environment for testing cross-site scripting, SQL injection, and other attacks. The application offers multiple levels of security, allowing users to start with unrestricted HTML and JavaScript code execution before moving on to more complex settings with advanced validation mechanisms. This approach helps to understand how security measures affect the success rate of attacks.
DVWA should first be deployed in a test environment, usually a virtual machine (and never in production, as the application is obviously very vulnerable).
4. bWAPP (Buggy Web Application)
This web application contains over 100 vulnerabilities and offers a deep dive into web security, including cross-site scripting, API security flaws, and cross-site request forgery (CSRF). It allows users to test persistent XSS, where embedded scripts are executed every time a user loads a web page. Its flexibility and comprehensiveness make it a great tool for both beginners and experienced security professionals.
5. Google XSS Game
Google’s XSS Game is an interactive, browser-based learning tool that contains six tasks that become increasingly difficult with each level. Each of them requires creation of a cross-site scripting payload that triggers a notification in the user’s browser, demonstrating how attackers manipulate input fields, event handlers, and JavaScript execution. This is a great starting point for beginners who want to learn about XSS. The tasks also cover CSS-based injection attacks and web browser security mechanisms.
6. alert(1) to win XSS Challenge
This set of challenges is entirely dedicated to cross-site scripting, and they get more difficult with each step. The platform allows users to execute JavaScript payloads under restrictive conditions. Challenges include bypassing filtering mechanisms, injecting scripts using iframe-based techniques, and using img src tags to execute malicious code. The format of the challenges encourages creative problem-solving and helps users understand how cross-site scripting payloads can be obfuscated to bypass security measures and avoid XSS filters.
7. OWASP WebGoat
This is a structured, lesson-based learning platform that provides tutorials on a range of security vulnerabilities, including cross-site scripting. Users learn by implementing client-side scripts, bypassing validation mechanisms, and exploiting browser flaws. Unlike other platforms, WebGoat provides real-world examples of vulnerabilities with step-by-step instructions, making it especially useful for those who prefer a structured approach to learning. The resource also shows how XSS filters and security headers such as CSP can help mitigate risks.
WebGoat must first be deployed in a test environment, usually a virtual machine.
8. Acunetix VulnWeb
Acunetix by Invicti’s VulnWeb is a set of intentionally vulnerable web applications designed for testing security tools and pentesting. Unlike lab-based platforms, these test sites simulate real applications, allowing users to practice finding and exploiting XSS vulnerabilities in realistic environments. Specialists can analyze how modern defenses interact with different attack vectors and improve their testing skills accordingly. The platform also shows how malware can spread through cross-site scripting attacks.
Invicti also provides another set of vulnerable web applications for testing: TestInvicti.
Conclusion
With these resources, specialists can better understand how cross-site scripting attacks work and how to protect web applications from them. Happy ethical hacking!
