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Regex Tester

Test regular expressions against sample text with live match highlighting.

FreeNo loginBrowser basedPrivacy friendly
By MerQPrime Editorial TeamUpdated 2026-06-20Reviewed 2026-06-20Editorial policy
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Overview

About the Regex Tester

Build and debug regular expressions with instant feedback. Enter your pattern and test string to see matches highlighted, groups extracted and errors explained — all without leaving your browser.

Benefits

How it works

  1. 1Enter your regular expression pattern in the input field.
  2. 2Paste or type the text you want to test against.
  3. 3Toggle flags such as global, case-insensitive and multiline.
  4. 4Review matches, capture groups and any syntax errors in real time.

Applications

Use cases

  • Validate form input patterns before deploying to production.
  • Extract structured data from logs and unstructured text.
  • Debug complex regex used in search-and-replace workflows.
  • Learn regex syntax by experimenting with live examples.

Support

Frequently asked questions

Which regex flavor is supported?
This tool uses JavaScript's built-in regular expression engine, which follows ECMAScript syntax.
Can I test capture groups?
Yes. Matched groups are listed so you can verify named and numbered captures.
Why does my pattern show an error?
Common issues include unescaped special characters, unclosed groups or brackets, and invalid quantifiers. The error message describes what went wrong.

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Related tools, guides & pages

Regex Tester (Match & Debug Online) | MerQPrime