Regex Tester
Build and test regular expressions against sample text with highlighted matches.
How to use the Regex Tester
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Enter your regular expression and flags.
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Paste the text to test against.
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Review highlighted matches and groups.
What is a regex tester?
A regex tester lets you experiment with regular expressions and immediately see what they match in real text. This tool uses the browser's JavaScript regex engine, supports flags like global, case-insensitive and multiline, highlights every match and lists capture groups — so you can refine patterns quickly and confidently.
Key features
- Live, highlighted matches as you type
- Toggle flags: g, i, m, s, u, y
- Capture-group breakdown
- Match count and clear error messages
Frequently asked questions
Which regex flavour does this use?
JavaScript (ECMAScript) regular expressions, exactly as they behave in browsers and Node.js.
Which flags are supported?
global (g), case-insensitive (i), multiline (m), dotAll (s), unicode (u) and sticky (y).
Does it show capture groups?
Yes — each match lists its numbered capture groups so you can verify your pattern.