Regular Expression Tester & Debugger

Regex • 100% Client-Side Processing

Interactive JavaScript regex tester with ReDoS protection. Test expressions with flags (g, i, m, s, u), highlight matches in real time, and extract capture groups.

Privacy First: Regular Expression Tester & Debugger executes 100% locally in your web browser. No inputs or generated outputs leave your device.

Zero Server Transmission

Regular Expression Pattern

Flags (g, i, m, s)

Test String

Matches (2) — Execution: 0.13ms

Match #1: “[email protected]” (Index 8)

Groups: $1: "support", $2: "devutility.site"

Match #2: “[email protected]” (Index 35)

Groups: $1: "billing", $2: "example.com"

Tool Chaining — Continue Workflow

Take your result from Regular Expression Tester & Debugger directly into companion utilities:

Regex Pattern Library & Cheatsheet Regex String Escape Helper

How to Use

Enter your regex pattern and select flags (g, i, m).
Type or paste test string in the text area.
View matches, match indices, and capture group details.

Key Features

•Real-time match highlighting
•Capture groups extraction
•ReDoS catastrophic backtracking safeguard
•Common pattern presets

Technical Scope & Limitations

• Uses JavaScript RegExp engine; PCRE lookbehinds or specific non-JS extensions may behave differently.