Regex Tester

How to use it

1. Type your pattern (for example (\d{4})-(\d{2})-(\d{2})) into the pattern box.
2. Choose flags — g for global, i for case-insensitive, m for multiline.
3. Watch matches highlight live as you type in the test text.
4. Open Matches & capture groups to see what each group captured per match.
5. Enter a replacement to preview String.replace output.

Common use cases

• Validating input formats — phone numbers, dates, emails and slugs against a real sample set.
• Extracting parts of log lines — use capture groups to pull timestamps or error codes out of mixed text.
• Learning backreferences — build a replacement like $1/$2 and see the result instantly instead of guessing.

FAQ

Q: Which regex dialect is used? A: The JavaScript RegExp engine (ECMAScript). It is close to PCRE for everyday patterns but differs on some advanced features — test anything ported from another language.

Q: My pattern matches in another tool but not here — why? A: Differences usually come from flags (the g flag changes match iteration) or from engine-specific features. Check flags first, then the pattern itself.

Q: Can I test Unicode and Chinese text? A: Yes. JavaScript regex operates on UTF-16 code units; for broad character matching use the u flag and escapes like \p{L} with a recent browser.