Crab Regex Tester

Test regular expressions against sample text in real-time. See all matches highlighted with their positions as you type. Supports JavaScript regex syntax with customizable flags. Essential for developers writing search patterns, data validation rules, or text parsing logic.

What regex flags are supported?

All JavaScript regex flags: g (global), i (case-insensitive), m (multiline), s (dotAll), u (unicode), and y (sticky). The default is "gi" which matches all occurrences regardless of case — the most common use case. Change flags to match your specific needs.

Who uses a regex tester?

Developers writing form validation (email, phone, zip code patterns), data engineers parsing log files, SEO professionals writing redirect rules, content managers building search-and-replace patterns, and anyone who works with text patterns regularly. If you've ever asked ChatGPT or Stack Overflow "what regex matches X" — this tool lets you test the answer before using it in your code.