onul.works

Regex Tester

Run a regex test online with live match highlights, match counts, indexes, and JSON results.

⌘ Runs in browser ◴ No data stored ⌁ Free
Regex and test text
Match results
Match count, indexes, and values appear as JSON.

How to use

  1. 1 Enter your regular expression pattern.
  2. 2 Turn on the g, i, m, s, or u flags as needed.
  3. 3 Paste the test string and review the regex test matches.
  4. 4 Adjust the pattern using the error message or highlighted results.

Common use cases

  • Email or ID pattern checks
  • Log string regular expression matching tests
  • JavaScript RegExp g/i/m/s/u flag result comparison

Frequently asked questions

Which regular expression options are supported?

Enter a pattern and test string, then toggle the g, i, m, s, and u flags. When the global flag is enabled, all matches are shown.

How are regex test matches displayed?

Matched text is highlighted, and the result includes the match count plus each match start and end position. You can paste into or clear the test string field.

Which regex syntax does it use?

It uses the browser JavaScript RegExp syntax. Invalid patterns are shown as errors, and without the g flag only the first match is found.

Related workflow

Regex TesterFit the pattern against sample text first to define what should match. → Cron GeneratorIf the pattern runs on a schedule, clarify that timing with a Cron expression. → Diff ViewerAfter changing the pattern or test text, compare how the result changed.