Regex Tester
Type a pattern, see matches highlighted instantly with capture groups listed. JavaScript regex engine — everything stays on your device.
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Type a pattern and some text.
Which regex flavor is this?
JavaScript (ECMAScript) — the same engine your browser uses. Most patterns port directly from PCRE, but lookbehind and Unicode classes follow the JavaScript spec.
Is my text uploaded?
No. Matching runs entirely in your browser — safe for logs, code and customer data.
Why does my pattern hang on long text?
Nested quantifiers like (a+)+ can cause catastrophic backtracking. This tester caps evaluation to keep the page responsive, but simplifying the pattern is the real fix.