Regex Tester
Test regular expressions live.
Enter a regular expression and a test string to see matches and capture groups live. Toggle the g, i, m, s and u flags. Everything runs locally in your browser using the JavaScript regex engine.
Your input is processed locally in your browser — nothing is uploaded, stored or logged.
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How it works
- 1 Type your regular expression.
- 2 Toggle the flags you need.
- 3 Paste a test string to see matches and groups.
Common use cases
- Build and debug a pattern.
- Check capture groups.
- Validate input formats.
- Learn how a regex behaves.
Frequently asked questions
Is my input sent to a server?
No. Everything runs locally in your browser — your input is never uploaded, stored or logged.
Which regex flavour is used?
JavaScript's RegExp engine, matching what runs in browsers and Node.js.
Is there an input limit?
Test text is capped at 50,000 characters to avoid slow patterns (catastrophic backtracking) freezing the page.
Is it really free?
Yes — free, with no signup and no limits.