Debug JavaScript regex patterns
Test a pattern against real text, adjust JavaScript flags and see match positions without wiring up a temporary script or console snippet.
Regex Tester
Test regex matches and replacement output.
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Build and debug regular expressions with live matches, flags and replacement previews.
- Pattern testing
- Regex flags
- Match positions
- Replacement preview
Preview replacement output
Use the replacement field to check how a find-and-replace operation will change content before applying it in code, spreadsheets or CMS fields.
Review captured groups
Each match output includes captured groups when the pattern contains parentheses, which makes extraction patterns easier to inspect.
Keep test data local
Regex matching and replacement previews run in your browser, so pasted logs, samples and draft text do not need to be sent to a server.
Frequently asked questions
It uses the JavaScript RegExp engine available in your browser, so patterns and flags should follow JavaScript regular expression syntax.
No. Enter only the pattern text, then add flags like g, i or m in the flags field or by using the flag buttons.
Yes. Add replacement text and the tool shows the replaced output alongside the match list.
No. Matching, group extraction and replacement previews run locally in your browser.