How do I test a regex pattern online?

Paste your regular expression into the Regex Tester, enter your test data, and see matches highlighted in real time. The tool shows capture groups, explains pattern components, and flags errors.

What is a capture group in regex?

Parentheses () create a capture group that extracts a specific portion of the match. For example, (\d{4})-(\d{2}) applied to '2026-04' captures '2026' in group 1 and '04' in group 2.

What does the g flag do in regex?

The g (global) flag finds all matches in the string, not just the first one. Without it, most regex functions stop after the first match.

How to Test Regular Expressions Online

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