About Regex Tester

Regex Tester is a free, client-side tool that lets you test and debug regular expressions in real time. Built for developers, students, and anyone who works with pattern matching.

Features

• Real-time regex matching with live highlighting
• Support for JavaScript regex flags (g, i, m, s, u)
• Capture group display with detailed match info
• Regex replace with group references ($1, $2, etc.)
• Common pattern library for quick access
• Error highlighting for invalid patterns
• 100% client-side — your data never leaves your browser

Privacy

All processing happens entirely in your browser. No text data is ever sent to any server.