Regex Tester
Test a regular expression against your text and see every match highlighted in place, with capture groups listed below. An invalid pattern gets a clear error message instead of a blank screen.
Matches: 0
How to use
- Type your regular expression and tick the flags you need.
- Paste the text you want to test it against.
- Click Test regex — matches are highlighted in the text and every capture group is listed below.
Frequently asked questions
What is a regular expression?
A regular expression (regex) is a pattern for matching text — for example \d+ matches one or more digits and \b\w+@\w+\.\w+\b matches email-like addresses. It is used for searching, validating and replacing text in code.
What do the flags do?
g finds every match instead of stopping at the first; i ignores upper/lower case; m makes ^ and $ match at each line start and end; s lets . match newlines too; u enables full Unicode mode.
Why does my pattern show an error?
Common causes are an unclosed bracket or parenthesis, a stray backslash at the end, or a quantifier with nothing to repeat. The error message names the problem so you can fix that spot.
Does my pattern or text leave my device?
No. Testing runs entirely in your browser with JavaScript. Nothing is uploaded or logged. Use it as a free regex tester online — no signup, nothing to install.
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