Regex Library — Common Regular Expressions Reference

Browse a curated library of common regular expressions for email, URL, phone, date, and more. Copy patterns instantly. Free regex reference tool.

26 patterns

Email Address

validation

Validates a standard email address format

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

Example: user@example.com

URL (http/https)

validation

url

Matches http and https URLs

https?:\/\/(www\.)?[-a-zA-Z0-9@:%._+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_+.~#?&/=]*)

Example: https://example.com/path?q=1

IPv4 Address

network

validation

Validates an IPv4 address (0.0.0.0 – 255.255.255.255)

^((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]?)$

Example: 192.168.1.1

IPv6 Address

network

validation

Matches a full IPv6 address

^([0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}$

Example: 2001:0db8:85a3:0000:0000:8a2e:0370:7334

Phone (US)

validation

phone

Matches US phone numbers in various formats

^(\+1)?[\s.-]?$?[0-9]{3}$?[\s.-]?[0-9]{3}[\s.-]?[0-9]{4}$

Example: (555) 123-4567

Date (YYYY-MM-DD)

date

validation

Validates ISO 8601 date format

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

Example: 2024-03-15

Date (MM/DD/YYYY)

date

validation

Validates US date format

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

Example: 03/15/2024

Time (HH:MM)

date

validation

Validates 24-hour time format

^([01]?[0-9]|2[0-3]):[0-5][0-9]$

Example: 14:30

Credit Card

validation

payment

Matches Visa, Mastercard, Amex, Discover card numbers

^(?:4[0-9]{12}(?:[0-9]{3})?|5[1-5][0-9]{14}|3[47][0-9]{13}|3(?:0[0-5]|[68][0-9])[0-9]{11}|6(?:011|5[0-9]{2})[0-9]{12})$

Example: 4111111111111111

ZIP Code (US)

validation

address

Validates US ZIP codes (5-digit or ZIP+4)

^\d{5}(-\d{4})?$

Example: 90210 or 90210-1234

Hex Color

css

color

Matches 3 or 6 digit hex color codes

^#([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3})$

Example: #FF5733 or #F53

RGB Color

css

color

Matches CSS rgb() color values

^rgb$\s*(\d{1,3})\s*,\s*(\d{1,3})\s*,\s*(\d{1,3})\s*$$

Example: rgb(255, 87, 51)

Slug

url

validation

Validates URL-friendly slugs

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

Example: my-blog-post-title

Username

validation

auth

Alphanumeric username, 3–20 chars, underscores allowed

^[a-zA-Z0-9_]{3,20}$

Example: john_doe123

Strong Password

validation

auth

security

Min 8 chars, uppercase, lowercase, digit, special char

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

Example: P@ssw0rd!

JWT Token

auth

security

Matches a JSON Web Token (3 base64url parts)

^[A-Za-z0-9-_]+\.[A-Za-z0-9-_]+\.[A-Za-z0-9-_]*$

Example: eyJ...header.payload.signature

UUID v4

validation

Validates a UUID v4 string

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

Example: 550e8400-e29b-41d4-a716-446655440000

Semantic Version

validation

versioning

Validates semver strings like 1.2.3 or 1.0.0-alpha.1

^(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)(?:-((?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)(?:\.(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?(?:\+([0-9a-zA-Z-]+(?:\.[0-9a-zA-Z-]+)*))?$

Example: 1.2.3 or 2.0.0-beta.1

HTML Tag

html

parsing

Matches HTML tags with content (non-void elements)

<([a-z][a-z0-9]*)\b[^>]*>(.*?)<\/\1>

Example: <div class="foo">content</div>

Markdown Link

markdown

parsing

Matches Markdown hyperlinks

\[([^\[]+)\]$(https?://[^$]+)\)

Example: [Google](https://google.com)

File Extension

files

validation

Matches common file extensions

\.(jpg|jpeg|png|gif|webp|svg|pdf|doc|docx|xls|xlsx|zip|tar|gz)$

Example: document.pdf

IP + Port

network

validation

Matches IPv4:port combinations

^((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]?):([0-9]{1,4}|[1-5][0-9]{4}|6[0-4][0-9]{3}|65[0-4][0-9]{2}|655[0-2][0-9]|6553[0-5])$

Example: 192.168.1.1:8080

Git Commit Hash

git

validation

Matches short (7) or full (40) git commit hashes

^[0-9a-f]{7,40}$

Example: a1b2c3d or a1b2c3d4e5f6...

Whitespace Only

string

validation

Matches strings that are empty or contain only whitespace

^\s*$

Example: (spaces only)

Integer

number

validation

Matches positive or negative integers

^-?\d+$

Example: 42 or -17

Decimal Number

number

validation

Matches integers and decimal numbers

^-?\d+(\.\d+)?$

Example: 3.14 or -2.5

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What is Regex Library?

Regex Library is a free, searchable collection of common regular expressions for developers. Browse patterns for email, URL, phone, date, color, security, and more. Copy any pattern with one click and use it directly in your code.

How to Use Regex Library

Search by name, description, or tag using the search box
Filter by category using the tag buttons
Click the copy button on any pattern to copy it to your clipboard
Paste the pattern into your code or use the Regex Tester to test it

Features

26 curated patterns covering common use cases
Search by name, description, or tag
Filter by category: validation, auth, network, date, CSS, and more
One-click copy for each pattern

FAQ

Are these patterns production-ready?

These patterns cover the most common cases but may need adjustment for edge cases in your specific use case. Always test patterns against your actual data before deploying to production.

How do I test a pattern?

Copy the pattern and paste it into the Regex Tester tool on this site to test it against your own input strings.

What regex flavor do these use?

All patterns use JavaScript-compatible regex syntax, which is compatible with most modern programming languages including Python, Java, and Go with minor adjustments.