Regex Tester

Build, test, and debug Regular Expressions in real-time. Matches and capture groups are evaluated instantly as you type.

/ /
Common Flags:
g Global i Ignore Case m Multiline s Dotall

Match Results

Highlighted Text
Match Details 0 Matches
No matches found.

Regex Evaluation Standards

Native JS Engine

This tool uses your browser's native V8 (or SpiderMonkey) RegExp engine. It processes ECMA-262 standard regular expressions identically to how they will execute in your actual JavaScript code.

Real-Time XSS Protection

When highlighting syntax, the test string is broken apart and completely sanitized before being rendered to the DOM. This prevents HTML injection and malicious XSS execution if testing raw HTML code.

Infinite Loop Guard

Zero-length matches (like ^ or .*) can cause standard exec() loops to crash browsers instantly. This tool utilizes manual index increments to guarantee stable real-time evaluation without locking up your tab.