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regex.199xc.com is a lightweight regular expression tester that lets you quickly verify matching and replacement in your browser. The page stays simple and focuses on one flow: enter a regex, see matches, apply replacement.

Purpose

No installation needed; debug and validate regex for development and data cleaning.

How it works

Runs locally with the browser regex engine; nothing is uploaded.

Scope

Syntax follows the JavaScript RegExp engine; other engines may differ slightly.

What it can do

  • Match and highlight results in real time.
  • Show each match’s position, length and capture groups.
  • Support g/i/m/s/u/y flags.
  • Support text replacement with $1, $& etc.
  • Provide clear syntax error messages.