Regex Tester
Tests a regular expression against your sample text as you type: matches are highlighted, capture groups listed, and the pattern itself is broken down token by token into a plain-English explanation. Includes a live replace preview with backreference support, a cheat sheet, common-pattern presets, and shareable links that encode the whole setup.
Runs 100% in your browser — nothing you paste leaves your device.
Read the full guide to this tool
Notes
- The tester uses the JavaScript (ECMAScript) regex flavor — close to PCRE, but without atomic groups, possessive quantifiers, recursion, \A/\z anchors, or inline flags like (?i).
- A pattern that backtracks catastrophically can freeze the tab; test long inputs with care.
- Runs 100% in your browser — nothing you paste leaves your device.
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