Regex Tester
Test regular expressions.
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About Regex Tester
Test and debug regular expressions in real time. Type a pattern, flip the global, ignore-case, multiline, and dotall flags, and paste any test string. Every match is highlighted right inside your text, listed with its capture groups and character index, and totaled with a live match count. Invalid patterns show a clear error instead of crashing.
This regex tester is completely free with no sign-up, no ads, and no limits. It runs entirely in your browser using the built-in JavaScript regex engine, so your patterns and test strings never leave your device and nothing is ever uploaded to a server.
Frequently asked questions
- Is this regex tester free to use?
- Yes, it is 100% free with no account, no sign-up, and no usage limits. Test as many patterns and strings as you like.
- Is my data uploaded anywhere?
- No. The tool runs entirely in your browser using JavaScript's built-in regular expression engine. Your pattern and test string never leave your device and are never sent to any server.
- Which regex flags are supported?
- You can toggle the four most common JavaScript flags: g (global, find all matches), i (ignore case), m (multiline, so ^ and $ match line breaks), and s (dotall, so the dot matches newlines).
- What regex syntax does it use?
- It uses the standard JavaScript RegExp syntax, the same engine found in every modern browser and Node.js. That includes character classes, quantifiers, anchors, lookaheads, and both numbered and named capture groups.
- Does it show capture groups?
- Yes. Each match is listed with its full text, its character index in the string, and every numbered ($1, $2) and named (<name>) capture group, so you can see exactly what each part of your pattern captured.
- Why does turning off the global flag only show one match?
- That is how JavaScript regular expressions actually behave. Without the g flag a regex stops after the first match. Turn on the g flag to find and highlight every match in the test string.