Regex Tester

Tests a pattern against your browser's real RegExp engine — there's no separate regex implementation here to disagree with your JavaScript, Python, or any other engine's exact behavior, but since JS regex is one of the most common flavors this covers the vast majority of everyday cases.

Pattern

/ /

Global

Ignore case

Multiline

Dot-all

Quick patterns

Illustrative common patterns — not exhaustive or RFC-perfect (email addresses in particular have a famously huge fully-correct grammar); good enough for everyday validation, not a substitute for testing against real-world data.

Test string Replacement (optional — preview only, uses $1/$2 for capture groups)