What regex flavour does this tool use?

This tool uses JavaScript's built-in RegExp engine, which supports ECMAScript regular expressions. This includes standard features like character classes, quantifiers, groups, lookaheads, and named captures. Some advanced features like lookbehinds are supported in modern browsers.

How do I test regex flags?

You can set flags using the flag toggles: g (global - find all matches), i (case-insensitive), m (multiline - ^ and $ match line boundaries), s (dotAll - . matches newlines), and u (unicode).

🔎 Utilities

Regex Tester & Explainer

Test regular expressions with live match highlighting and capture group display. Get a plain-English breakdown of what each part of your pattern does — great for learning and debugging.

🔍 Pattern

/ / gi

Flags:

Quick patterns:

Email URL IPv4 Date Name Hex color

📝 Test String

📋 Regex Quick Reference

Characters

\d Digit (0–9)

\w Word char (a-z, A-Z, 0-9, _)

\s Whitespace

. Any char except newline

[abc] Character class

[^abc] Negated class

Quantifiers

* 0 or more

+ 1 or more

? 0 or 1 (optional)

{n,m} Between n and m

*? Lazy (minimal match)

Anchors

^ Start of string/line

$ End of string/line

\b Word boundary

Groups

(abc) Capture group

(?:abc) Non-capture group

(?<name>) Named group

a|b Alternation (a or b)

📖 How to Use This Tool

▼

Enter a pattern in the regex field

Paste test text — matches highlight live

View capture groups and values

Use the cheatsheet for syntax help

📝 Examples

Emails

Input: [a-z]+@[a-z]+\.[a-z]+

Output: Highlights all emails in text