Regex tester

Test JavaScript regular expressions locally and inspect complete matches, captures and UTF-16 offsets.

Tool guide

How to use Regex tester

Test JavaScript regular expressions locally and inspect complete matches, captures and UTF-16 offsets.

  1. Paste text and choose the settings. Work starts only when you choose the tool action; samples are fictitious. No account or file upload is required.
  2. 1 MiB per text input · 4 MiB complete output · browser-only processing. 2,048-byte pattern · 1,000 matches · 100 captures · 2-second worker deadline.
  3. Global matching is automatic. Offsets are zero-based UTF-16 code units, end exclusive. Unmatched captures are null. Expensive patterns time out; other regex languages can behave differently. Exceeding a limit rejects the complete report.
  4. Review the result before downloading. Cancel stops the local worker; editing, Clear or leaving discards the old result and download link. Text and results are not saved to your account. Already-downloaded files remain on your device.
Read the full guide