Flags:

Test String0 matches

Replace:

Match Results

Enter a pattern and test string to see matches

Quick Reference — click to insert

.Any character

\dDigit [0-9]

\DNon-digit

\wWord char [a-zA-Z0-9_]

\WNon-word char

\sWhitespace

\SNon-whitespace

^Start of string

$End of string

\bWord boundary

*0 or more

+1 or more

?0 or 1 (optional)

{n,m}Between n and m times

()Capture group

(?:)Non-capture group

(?=)Positive lookahead

(?!)Negative lookahead

[a-z]Character range

[^abc]Negated class

a|bAlternation (or)

\nNewline

EmailEmail address pattern

URLURL pattern

DateYYYY-MM-DD date

PhoneUS phone number

Hex ColorCSS hex color

IPIPv4 address

The Most Powerful Online Regex Tester

Everything you need to master regular expressions

🎨

Live Match Highlighting

Matches are highlighted in real-time directly in your test string — different colors for each match number.

🔍

Group Capture Display

See every captured group for every match — their index, value, and position in the string.

🔄

Replace Mode

Test find-and-replace operations with support for back-references like $1, $2 for captured groups.

📖

Built-in Cheat Sheet

Click any pattern from the quick reference to insert it instantly. Includes common email, URL, and date patterns.

Frequently Asked Questions

What does the 'g' flag do?

The global flag makes the regex find all matches instead of stopping at the first one. Without it, only the first match is found.

How do I use captured groups in replace?

In replace mode, use $1, $2, etc. to reference captured groups. For example, pattern (\w+) (\w+) with replacement $2 $1 would swap two words.

What flavour of regex is used?

This tool uses JavaScript's built-in RegExp engine (ECMAScript), which supports most common regex features including lookaheads, named groups, and unicode mode.

What does the 's' flag do?

The dotAll flag makes the dot (.) match any character including newlines. By default, the dot does not match line breaks.

Regex Tester — Complete Guide

A regex tester lets you write and test regular expressions interactively against sample text. It highlights matches in real time, helping developers build and debug regex patterns for data validation, text parsing, and search operations.

✅ Real-time matching

See matches highlighted instantly as you type your regex — no need to run code to verify that your pattern works correctly on sample input.

📋 Common patterns

Use preset patterns for common tasks like email validation, phone numbers, URLs, IP addresses, and date formats — saving time on frequently needed regex.

🔍 Group extraction

Test capture groups and named groups to verify that your regex correctly extracts the specific parts of a string you need in your application.

🚩 Flags & modifiers

Test your regex with different flags — case-insensitive (i), multiline (m), global (g) — to understand how they affect pattern matching behavior.

Regular expressions are a powerful text processing language supported by virtually every programming language and text tool. Learning regex unlocks capabilities like data validation, log parsing, search-and-replace operations, and text extraction that would require many more lines of procedural code to accomplish otherwise.

Regex Tester & Debugger