Simon Willison’s Weblog

OWASP: XSS Prevention Cheat Sheet. Comprehensive set of rules for avoiding XSS—there’s a bit more to it than just escaping all output variables, since you have to take markup context in to account.

Posted 24th January 2009 at 11:58 pm

Recent articles

OpenAI are quietly adopting skills, now available in ChatGPT and Codex CLI - 12th December 2025
GPT-5.2 - 11th December 2025
Useful patterns for building HTML tools - 10th December 2025

markup 8 owasp 4 security 569 xss 60

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