A regular expression (regex) is a pattern for matching text. This tester lets you write a pattern, toggle flags, and see exactly what it matches in your sample text in real time — with every match and capture group highlighted. Everything runs locally in your browser.
How to use it
- Type your regular expression in the pattern field.
- Toggle flags like g (global), i (case-insensitive) and m (multiline).
- Paste your test text below.
- Matches are highlighted live, with capture groups listed.
About Regex Tester
Regular expressions are one of the most powerful — and most error-prone — tools in a developer’s kit. They power search-and-replace, input validation, log parsing, and routing. But getting a pattern exactly right usually takes trial and error, and a tiny mistake can match too much or nothing at all. A live tester removes the guesswork: you see immediately what matches, which groups are captured, and how flags change behaviour. This uses the browser’s native JavaScript regex engine, so what you see matches how JS will behave in your code. Nothing is uploaded.
FAQ
Which regex flavour does this use?
JavaScript (ECMAScript) regular expressions, the same engine browsers and Node.js use. Most patterns are portable, but some PCRE-only features differ.
What do the flags mean?
g matches all occurrences, i ignores case, m makes ^ and $ match line boundaries, s lets . match newlines, and u enables full Unicode.
Is my text uploaded?
No. Matching runs entirely in your browser.