Regex Tester

Build and debug regular expressions with instant feedback. See every match highlighted and every capture group in a table.

How to use the Regex Tester

  1. Add your text, file or details in the tool above.
  2. Adjust the settings to get the result you want.
  3. Copy or download your result. Nothing is uploaded.

What you can use it for

  • Debug validation patterns for forms
  • Build find-and-replace rules
  • Learn regex with live feedback

Private by design

The Regex Tester runs entirely in your browser. Your text and files are never uploaded or stored on a server, so it is safe for work documents and personal information. It is free, with no sign-up and no limits on how often you use it.

Frequently asked questions

Which regex flavour does it use?

JavaScript (ECMAScript), the same engine your browser uses.

How do I reference groups in a replacement?

Use $1, $2 for numbered groups.

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