Regex Tester

Test patterns, inspect matches and groups, and preview replacements. All processing stays in your browser.

Matches

Run Test to see matches here.

About Regex Tester

Build and debug regular expressions with live feedback. See every match and capture group highlighted against your sample text and preview replacements before applying them.

Features

  • Highlight matches and capture groups in real time
  • Toggle flags like global, ignore-case, and multiline
  • Preview replacements with substitution patterns
  • Get readable errors for invalid patterns

How to use

  1. 1Enter your regular expression and choose flags.
  2. 2Paste sample text to test against.
  3. 3Review highlighted matches and optional replacements.

Frequently Asked Questions

Which regex syntax is supported?
The tester uses the JavaScript regular expression engine, including flags and named capture groups.
Is my text private?
Yes. Matching runs in your browser, so your patterns and sample text stay on your device.
Can I preview replacements?
Yes. Provide a replacement string to see the substituted output instantly.

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