🎯 Regex Tester
Test regex online free — live match highlighting, capture group inspection, flags support and a library of common patterns (email, URL, IP, phone). JavaScript regex engine, fully in-browser.
Highlighted matches
How to use the Regex Tester
- 1 Type your regular expression and pick flags (g, i, m…).
- 2 Paste test text — matches highlight live as you type.
- 3 Inspect each match and its capture groups in the list below.
Frequently asked questions
Which regex engine does this use?
JavaScript’s built-in RegExp engine — identical behavior to Node.js and browsers. Most patterns also work in Python/Java with minor syntax differences.
What do the flags mean?
g = find all matches (not just the first), i = case-insensitive, m = ^ and $ match per line, s = dot matches newlines, u = full unicode mode.
How do I match an email address?
Use the Email preset button below the pattern field for a practical pattern. Note that fully RFC-compliant email regex is famously complex — presets favor real-world usage.
Is my test data private?
Yes — matching runs in your browser. Logs, tokens or personal data you test are never transmitted.