Regular Expression Tester
Type a pattern and see matches highlighted live in your test text, with capture groups listed for every match. Uses the JavaScript regex engine — what works here works in Node and the browser.
Quick reference: \d digit · \w word char · \s whitespace · . any char · + one or more · * zero or more · ? optional · ^ start · $ end · [abc] character set · (x) capture group · a{2,4} repetition range.
![Infographic: regex anatomy — the Indian mobile pattern [6-9]\d{9} decoded piece by piece with each token labeled](/img/regex-pattern-anatomy.svg)
Common patterns to steal
| Goal | Pattern |
|---|---|
| Email (practical) | [\w.+-]+@[\w-]+\.[\w.]{2,} |
| Indian mobile number | (\+91[\s-]?)?[6-9]\d{9} |
| URL | https?:\/\/[\w.-]+(\/\S*)? |
| Date YYYY-MM-DD | \d{4}-\d{2}-\d{2} |
| Trailing whitespace | [ \t]+$ (with m flag) |
| Duplicate words | \b(\w+)\s+\1\b |
Frequently asked questions
Which regex engine does this tester use?
JavaScript's built-in engine (ECMAScript) — the same one in Node.js and every browser. Most patterns transfer to Python, Java, and PCRE unchanged, but some advanced features differ: JavaScript lacks recursion and possessive quantifiers, for example.
What do the g, i, m, and s flags do?
g finds all matches instead of stopping at the first; i ignores letter case; m makes ^ and $ match at every line start and end instead of just the text's start and end; s makes the dot . also match newline characters.
Why does my pattern match too much?
Usually greedy quantifiers: .* grabs as much as possible. Make it lazy with .*? or, better, replace the dot with a specific negated set like [^"]* to stop at the next quote. Test here with realistic text — greedy surprises show up instantly in the highlighting.
Is my test text sent anywhere?
No — matching happens entirely in your browser as you type. Paste logs or real samples freely; nothing is transmitted.