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Regex Tester

Tries a regular expression against sample text and highlights everything it matches.

This tool runs entirely in your browser. Nothing you enter is uploaded, transmitted or stored anywhere.
g = all matches, i = ignore case, m = multiline, s = dot matches newline, u = unicode.
Leave empty to skip the replace preview. Use $1, $2 for capture groups.

Common questions

Which flavour of regex is this?
JavaScript regular expressions, since it runs in your browser. Most patterns are portable, but lookbehind and some named-group syntax differ from PCRE.
Can a pattern hang the page?
A pathological pattern can be very slow. The tester stops after a match limit and warns you rather than freezing.

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