Pattern Library

A curated collection of production-ready regular expressions. Search, filter, and copy patterns for your next project.

Looking for implementation guidance? Explore our regex engineering blog for performance checklists, migration playbooks, and practical validation strategies.

Validation

Email Address

Validate email addresses with RFC-compliant regex pattern.

^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$

Validation

Password Strength

At least 8 chars, 1 uppercase, 1 lowercase, 1 number, 1 special char.

^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[@$!%*?&])[A-Za-z\d@$!%*?&]{8,}$

Validation

IPv4 Address

Matches valid IPv4 addresses.

^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$

Validation

UUID v4

Matches a version 4 UUID.

^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$

Validation

Date (ISO 8601)

Matches dates in YYYY-MM-DD format.

^\d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12]\d|3[01])$

Web

URL Slug

Matches valid URL slugs (kebab-case).

^[a-z0-9]+(?:-[a-z0-9]+)*$

Web

Hex Color Code

Matches hex color codes (#FFF or #FFFFFF).

^#?([a-fA-F0-9]{6}|[a-fA-F0-9]{3})$

Web

HTML Tag

Matches opening and closing HTML tags.

<[^>]+>

Web

Twitter Handle

Matches a Twitter handle (username).

^@?(\w){1,15}$

Data

Simple JSON Object

Matches a simple flat JSON object (basic approximation).

\{\s*"[^"]+"\s*:\s*(?:"[^"]+"|\d+|true|false|null)\s*\}

Data

CSV Field

Matches a CSV field, handling quotes.

(?:^|,)(?:"([^"]*(?:""[^"]*)*)"|([^",]*))

Text

Duplicate Words

Finds duplicate words in a sentence.

\b(\w+)\s+\1\b

Text

Trailing Whitespace

Matches whitespace at the end of lines.

[ \t]+$

Text

Split CamelCase

Matches the position before capital letters to split CamelCase.

(?<=[a-z])(?=[A-Z])

Validation

Credit Card (Simple)

Matches major credit cards (Visa, MasterCard, Amex, Discover).

^(?:4[0-9]{12}(?:[0-9]{3})?|5[1-5][0-9]{14}|3[47][0-9]{13}|6(?:011|5[0-9]{2})[0-9]{12})$

Validation

US SSN

Matches US Social Security Numbers (XXX-XX-XXXX).

^(?!000|666|9\d\d)\d{3}-(?!00)\d{2}-(?!0000)\d{4}$

Validation

US Phone Number

Matches US phone numbers in various formats.

^$?([2-9][0-8][0-9])$?[-. ]?([2-9][0-9]{2})[-. ]?([0-9]{4})$

Validation

IPv6 Address

Matches standard IPv6 addresses.

^(?:[A-F0-9]{1,4}:){7}[A-F0-9]{1,4}$