Regex Tester
Test and debug regular expressions with real-time matching, capture groups, and replacement preview.
Local worker: 1,000ms budget; up to 1,000 matches, 10,000 pattern characters, 100,000 text/result characters and 10,000 capture values (UTF-16). Truncated matches have no replacement preview.
About Regex Tester
Try JavaScript regular expressions with matches, captures and replacement preview.
Enter a pattern without enclosing slashes, choose flags and provide test text. Results refresh after editing.
Copy the current matches or replacement when checking a parser or text cleanup rule.
The calculation or rendering runs in this browser tab. Copy, download and share actions make the chosen output available outside this tab.
Worked example
- Input / settings
- Pattern \d+, flags g, text Order 12 and 34, replacement #
- Action
- Run matching and replacement
- Result
- Matches 12 and 34; replacement Order # and #.
Scope and limits
- JavaScript syntax only; matching runs in a worker with a 1,000ms budget. Text/result are capped at 100,000 characters, patterns at 10,000 and matches at 1,000. Errors or edits invalidate old output.
Frequently asked questions
- Why can a valid pattern time out?
- Backtracking can take excessive time on some text. The worker is stopped so you can simplify the pattern or shorten the input.
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