Regex Tester — Online JavaScript Regular Expressions
Write a pattern, paste text, and watch matches update as you type — including group capture and a replacement preview for validating a real substitution.
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Nothing you enter here is sent anywhere. There is no file and no request to our server - the work is done in your browser and disappears when you close the page.
How It Works
- Enter — Fill in the values the tool asks for.
- Run — Press the button; an empty field is reported by name rather than read as zero.
- Read — The answer comes with the working behind it, so you can check the figure.
- Take it — Copy the result, or download it where the tool offers that.
Frequently Asked Questions
Which regex dialect is used?
JavaScript regular expressions, matching what your browser and Node runtimes execute. Flags g, i, m, s, u and y are supported, and an invalid pattern is reported instead of silently ignored.
How are the matches presented?
Each match is listed with its index, the captured groups and the literal text, with the matched spans highlighted inside the sample so you can see exactly what the engine consumed.