Regex Tester
Test a regular expression against your text, with flags and a live count of matches. Runs entirely in your browser.
Limits: 2,000 pattern characters · 100,000 text characters · 5,000 matches · 250 ms.
How to use
Pick a ready-made pattern or type your own, set flags, and enter test text. After a brief safety delay, matches are highlighted and listed with capture groups, and you can preview a find-and-replace using $1/$& — all privately in your browser.
FAQ
Which regex flavor is used?
It uses JavaScript (ECMAScript) regular expressions, running natively in your browser.
What do the flags mean?
g = global, i = case-insensitive, m = multiline, s = dotall, u = Unicode, y = sticky, and d exposes match indices. The newer v Unicode-sets flag is enabled only when your browser supports it.
Can I see capture groups and test a replacement?
Yes. Every match lists its numbered and named capture groups, and the Replace box previews the result live — you can use $1, $2 and $& just like String.replace.
What are the common patterns?
A library of 20 ready-made, tested patterns (email, URL, IPv4, UUID, hex color, date, time and more) so you do not have to write them from scratch.
Is my text uploaded?
No. The pattern and text never leave your browser.
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