Free Regex Tester — Live Match Highlighting, Capture Groups

Launch the tool

freeregextester.app

Open Regex Tester →

Features

Live match highlighting
Capture group display
Flag toggles (g, i, m, s, u, y)
Match count
Replace preview with substitution
JavaScript regex syntax (ECMAScript)
Ad-free, works offline

How it works

Open freeregextester.app
Type a regex pattern in the input
Paste test text in the text area
Watch matches highlight live, see capture groups

Common use cases

Building validation patterns for forms
Extracting data from text with capture groups
Testing log-parsing patterns
Debugging regex from existing code
Learning regex with instant feedback

How it compares

RegExr is the gold standard with community-shared patterns and a massive cheatsheet. Regex101 supports multiple flavors (Python, PHP, Go, PCRE). Freeregextester is simpler — ad-free JavaScript regex testing on one page.

Privacy

Patterns and test text stay in your browser. Safe to test against sensitive data.

Frequently asked questions

Which regex flavor does Freeregextester use?

JavaScript regex (ECMAScript). Same as what runs in browsers and Node.js.

Can I test Python or PCRE regex?

Not directly. For Python or PCRE, use Regex101 which supports multiple flavors.

Does it support named capture groups?

Yes. ECMAScript named capture groups (?<name>...) work.

Can I test substitution?

Yes. Enter a replacement pattern and see the transformed output live.

Is there a regex cheatsheet?

A basic reference is included inline. For deeper reference, consult MDN's regex documentation.

Is my test data sent anywhere?

No. Testing happens entirely in your browser.

Free Regex Tester — live match highlighting and capture groups