XSS Tester

Test strings for XSS vulnerabilities and generate context-safe encoded output for HTML, JavaScript, URL, and CSS

All processing happens in your browser. No data is uploaded.

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XSS Tester

Test strings for XSS vulnerabilities and generate context-safe encoded output for HTML, JavaScript, URL, and CSS

🔒All processing happens in your browser. No data is uploaded.

Educational Tool

This tool is for educational and defensive security purposes only. Use it to learn about XSS vulnerabilities and how to properly encode output in your applications.

Test String

Enter a string to test for XSS patterns...

Sample XSS Payloads

XSS Prevention Best Practices

Always encode output based on the context (HTML, JavaScript, URL, CSS) where user data is rendered.

Use Content Security Policy (CSP) headers to restrict inline scripts and untrusted sources.

Use textContent or innerText instead of innerHTML when inserting user-provided text into the DOM.

Validate and sanitize input on the server side, but always encode on output as the primary defense.

Use established libraries like DOMPurify for HTML sanitization when rich HTML content is needed.

Set the HttpOnly and Secure flags on cookies to prevent JavaScript access and ensure HTTPS transmission.