Regex Tester

Test a regular expression against sample text and see the matches.

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Frequently asked questions

What does the regex tester do?

It runs your regular expression against sample text and shows every match and captured group, so you can build and debug patterns quickly.

Which regex flavour is used?

PCRE (Perl-compatible), the same engine used by PHP and very close to JavaScript and Python. Common flags like case-insensitive and multiline are supported.

Why did my pattern time out?

Some patterns cause catastrophic backtracking on certain inputs. The tester limits execution time to stay responsive; simplify the pattern if it is rejected.