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Regex Tester (JavaScript)

Quickly debug regex patterns. See matches and capture groups and test a replacement string.

Pattern

Flags

Test text

Replacement (optional)

Matches

2 matches

#1 "test@example.com" @ 7
Groups: [1:"test"] [2:"example.com"]
#2 "a@b.co" @ 31
Groups: [1:"a"] [2:"b.co"]

Replace preview

How to use this tool

  1. Enter a regex pattern and flags.
  2. Paste test text.
  3. Review matches and replacement preview.

How to Use

Use the pattern + flags inputs to define your regex. Matches update instantly as you edit text.

How It Works

The tool uses the browser’s JavaScript RegExp engine to execute matches and replacements locally.

Key Features

  • Matches + groups
  • Flag support
  • Replace preview

Secure & Private

All processing is local in your browser.

Frequently Asked Questions

Which regex flavor is this?
JavaScript regular expressions (ECMAScript).
Can a regex freeze the page?
Some patterns can be slow on large inputs. If the page becomes slow, reduce input size or simplify the pattern.

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Privacy Notice

All processing happens inside your browser. No files or data are uploaded to our servers, ensuring your privacy is strongly protected.