Regex Tester
Test patterns with live match highlighting and group inspection.
Files and text are processed locally in your browser. Tools that must reach the network say so explicitly.
About the Regex Tester
Build and test regular expressions interactively. The Toolcenter Regex Tester highlights every match in your test string, lists match positions and capture groups in a table, previews a replace operation with $1/$<name> support, and includes a quick-reference cheat sheet. Uses the JavaScript regex engine.
How to use it
- 1Type your pattern and toggle flags (g, i, m, s, u, y).
- 2Paste a test string.
- 3See matches highlighted and listed with their groups.
- 4Try a replacement in the replace box.
Key features
- Live match highlighting
- Capture-group and index table
- Replace preview with backreferences
- Flag toggles and error messages
- Built-in syntax cheat sheet
Frequently asked questions
Which regex flavour is this?+
JavaScript (ECMAScript) regular expressions, the same engine used in Node.js and browsers.
How do I use named groups in a replacement?+
Reference them as $<name> in the replace field; numbered groups use $1, $2, and the whole match is $&.
What do the flags mean?+
g = all matches, i = case-insensitive, m = multiline anchors, s = dot matches newlines, u = Unicode, y = sticky.
Is my text uploaded?+
No. Matching runs in your browser.
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