Write a pattern, drop in a test string, see every match.
Live highlighting, capture groups, flags, replace and split modes — all running locally against JavaScript's native RegExp engine. Nothing is uploaded.
Tip: leave the global flag off to test a single match, or turn it on to find every occurrence.
Regex cheat sheet +
Four steps, working regex.
No manual required — here's the entire flow.
Enter your pattern
Type the regular expression into the field between the slashes. The pattern updates live as you type.
Add a test string
Paste or type the text you want to match against. Every match is highlighted instantly.
Toggle flags & modes
Flip g, i, m, s, u, or y to change how matching works. Switch to Replace or Split for other operations.
Inspect matches
See every match with its position, capture groups, and named groups — then copy the pattern when you're happy.
Built for iterating, not just matching.
The details that make writing and debugging regular expressions faster, without ever leaving your browser.
Runs on your device
Matching runs locally using JavaScript's native RegExp engine. Your pattern and test string never leave your device.
Live match highlighting
Matches highlight in the test string as you type, with a count of how many were found and exactly where they start.
Capture & named groups
Each match lists its numbered and named capture groups alongside the character index where it begins, so you can see exactly what your pattern pulled out.
Questions people actually ask.
The short answers — with the long ones one tap away.
How do I test a regular expression with this tool?+
Type or paste your pattern into the regex field, add your test string below, and matches highlight instantly. Flip flags or switch to Replace mode to iterate on your expression.
Is my data uploaded to a server?+
No. All matching runs locally in your browser using JavaScript's RegExp engine. Your pattern and test string never leave your device.
Which regex engine does this use?+
It uses the native JavaScript RegExp engine, so the syntax and behavior match what you get in Node.js, browser JavaScript, and most modern runtimes.
Can I see capture groups and named groups?+
Yes. Every match lists its numbered capture groups and any named groups, along with the character position where the match starts.
What flags can I toggle?+
You can toggle g (global), i (case-insensitive), m (multiline), s (dotAll), u (unicode), and y (sticky). The active flags are shown next to the pattern field.
Does this tool support find and replace?+
Yes. Switch to Replace mode, type a replacement string using $1, $2, or $<name> references, and the transformed output updates live.
Is this regex tester free to use?+
Yes, it's completely free with no account, no sign-up, and no limit on how many times you use it.