Regex Tester

Test regular expressions live — match highlighting, capture groups, replace preview and a cheat sheet. Runs in your browser, with runaway-pattern protection.

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/ / g
Test string matches update as you type
Result
Enter a pattern and some test text, or press Sample.
Matches 0 Groups 0 Time — Length 0

Cheat sheet

. any character
\d digit   \D non-digit
\w word char   \W non-word
\s whitespace   \S non-space
[abc] any of a, b, c
[^abc] none of them
[a-z] range
\b word boundary
* 0+   + 1+   ? 0 or 1
{2,5} 2 to 5 times
+? lazy (shortest match)
(…) capture group
(?:…) non-capturing
(?<n>…) named group
a|b either
^ start   $ end

About this tester

This uses the JavaScript (ECMAScript) regex engine, the same one your browser and Node.js use. Java's java.util.regex is very close, but differs on a few things — Java needs double backslashes in string literals ("\\d"), and supports possessive quantifiers (a++) which JavaScript does not.

Patterns run inside a Web Worker with a time limit, so a catastrophic pattern like (a+)+$ is stopped instead of freezing the page.

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