Regex Tester
FreeTest regular expressions with live highlighting, match groups, and cheat sheet
regexregular expressiontestpattern
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How it works
1
Write
Enter your regular expression pattern and optional flags in the pattern field.
2
Test
Type or paste test text and see matches highlighted in real time as you type.
3
Review
Inspect matched groups, capture groups, and match indices in the results panel.
Frequently asked questions
Is my text or regex sent to a server?+
No. All pattern matching runs in your browser using JavaScript's built-in RegExp engine. Your test data never leaves your device, so you can safely test patterns against sensitive text.
Which regex flavor does this use?+
It uses JavaScript's RegExp engine, which supports features like lookahead, lookbehind, named groups, and Unicode property escapes. Syntax from other flavors like PCRE may differ slightly.
What flags are supported?+
All standard JavaScript regex flags are supported: g (global), i (case insensitive), m (multiline), s (dotAll), u (unicode), and y (sticky).
Can I see capture groups?+
Yes. Named and numbered capture groups are displayed for each match. You can see exactly which part of the input each group captured, making it easy to debug complex patterns.
Does it highlight matches in real time?+
Yes. Matches are highlighted instantly as you type your pattern or modify the test text. There is no need to click a button, so you get immediate visual feedback.