Regex Tester
Regex Tester is a free online tool for testing regular expressions in real time. Enter a pattern and test text to instantly see all matches, toggle the global (g), ignore-case (i), and multiline (m) flags, and inspect each match's content, position, and capture groups in a results table. Built-in presets cover email, IPv4, time, and more.
All matching runs locally in your browser — your test text is never uploaded to any server, and no registration is needed. Handy for developers writing and debugging patterns, validating form rules, or grabbing a preset for a quick match.
How to Use
- Enter a regular expression, or pick one of the built-in presets
- Toggle the flags you need (global, ignore case, multiline)
- Paste the text you want to match into the test area
- Click Test to see match counts, positions, and capture group details
FAQ
Is this regex tester free?
Yes, it is completely free with no registration required and no usage limits.
Is my test text kept private?
Yes. Matching runs entirely in your browser — neither your pattern nor your test text is ever sent to a server.
Which regex flavor does it use?
It uses the JavaScript (ECMAScript) regex engine, identical to browsers and Node.js, with support for the g, i, and m flags. Note there are minor syntax differences from PCRE or Python regex.
Can I inspect capture groups?
Yes. The results table lists each match's index, matched content, position in the text, and the values of all capture groups — great for debugging complex patterns with groups.