Regex tester
Type a regular expression and some text to see every match highlighted as you type, with a table of capture groups, all JavaScript flags and a replace preview. Pick a common pattern to start quickly.
- ๐ Runs on your device
- โค 0 bytes uploaded
- ๐ด Works offline
- โ Free, no sign-up, no watermark
How to use Regex Tester
- Type your pattern (without the slashes).
- Turn flags on or off.
- Paste the text to search and see the matches.
- Turn on Replace to preview a replacement.
Is it private?
Yes. Regex Tester runs entirely in your web browser. What you type is never sent to Nolo or anyone else, and the page cannot send it anywhere: its security policy only allows it to talk to nolotools.com, which has no place to receive data. Nothing is stored either: close the page and it is gone. How Nolo works.
Questions and answers
Is my text sent to a server?
No. Everything runs in your browser and your text never leaves your device. The page is not allowed to talk to any other site, so it is safe to use with real data and secrets.
Which regex flavor does it use?
JavaScript (ECMAScript), using your browser's own engine, the same as Node.js. It supports lookbehind, named groups (?<name>โฆ), Unicode properties \p{L} with the u flag, and the s flag.
What happens if my regex is too slow?
Patterns run in a background worker. If one takes more than 2 seconds, usually from catastrophic backtracking such as (a+)+, it is stopped and you get a message instead of a frozen tab.
Why is only one match shown?
Without the g (global) flag JavaScript stops after the first match. Turn g on to find all matches.
How do I use groups in the replacement?
Use $1, $2 for numbered groups, $<name> for named groups, $& for the whole match and $$ for a literal dollar sign.