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Regex Tester & Debugger
Test JavaScript regular expressions live with match highlighting, capture groups and replace preview.
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About Regex Tester & Debugger
Regular expressions are a compact pattern language for searching and transforming text. Crafting them is famously error-prone, a stray quantifier or unescaped dot can change the meaning entirely.
This tester evaluates a JavaScript regular expression against your input in real time, highlights every match, lists capture groups, and previews the result of a replacement string. Everything runs locally in your browser.
Frequently asked questions
Which regex flavour is used?
JavaScript / ECMAScript via the native RegExp engine, including modern features like named groups, lookbehind and the d (indices) flag.
Can I test a replacement?
Yes, type a replacement pattern and the result is shown live. $1, $2, $<name> backreferences are supported.
Is my input sent anywhere?
No. The expression runs in your browser only.
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