ToolWren › Regex Tester

Regex Tester

Write a regular expression and test it against sample text in real time. See every match, its position and any capture groups instantly.

100% client-side · nothing is uploaded

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How to use the Regex Tester

Enter your regular expression and any flags (like g or i); or pick a ready-made one from Common patterns.
Paste your test text — matches are highlighted and listed with capture groups as you type.
Switch to Replace or Split mode to preview substitutions or splitting.
Use the built-in cheat sheet below for a quick syntax reference.

Privacy: this tool runs entirely in your browser. Your input is never sent to, received by, or stored on any server — there are no uploads and no tracking of what you enter.

About Regex Tester

Testing regular expressions

Enter a pattern and flags, then paste text to test. Matches are listed as you type, including the matched substring, its index and the contents of each capture group.

Flags

Use flags like g (global, find all matches), i (case-insensitive), m (multiline) and s (dotall). This tool uses the JavaScript regex engine.

Capture groups

Parentheses create capture groups. The tester shows each group's value per match, which is invaluable for extracting structured data from text.

Frequently asked questions

Which regex flavour is this?

JavaScript (ECMAScript) regular expressions, the same engine used in browsers and Node.js.

Does it support named groups?

Yes — named groups work, and their captured values appear alongside numbered groups.

Is my text uploaded?

No. Matching runs entirely in your browser.