Which regex flavor does this tool support?

Our tool currently supports the JavaScript (ECMAScript) regular expression flavor, as it runs directly in your web browser.

What are regex flags?

Flags are optional parameters that modify the behavior of the regex. Common flags include 'g' (global, find all matches), 'i' (case-insensitive), and 'm' (multiline).

Yes. All regex evaluation happens locally in your browser. Your test strings and regex patterns are never sent to our servers.

What regular expression flavors are supported?

The tool tests against JavaScript's RegExp engine. Most standard regex features like groups, lookaheads, character classes, and quantifiers are supported.

How do I match an email address with regex?

A common pattern is /^[\w.-]+@[\w.-]+\.[a-zA-Z]{2,}$/. However, email validation with regex is complex — for production, consider using a dedicated validation library.

What do the flags g, i, and m mean?

g (global) finds all matches, not just the first. i (case-insensitive) ignores case. m (multiline) makes ^ and $ match start/end of each line instead of the whole string.

How do I test a regex with capture groups?

Wrap parts of your pattern in parentheses, e.g., /(\d{4})-(\d{2})-(\d{2})/. The tool highlights each group and shows the captured values separately.

📋

Common Regex Patterns

Production-ready regular expressions for common validation tasks. Copy-paste these patterns into your code with confidence.

Contact Phone Numbers URLs & Web Network Date & Time Financial Security Code & Identifiers Text

Contact

Email (Basic)

Validates most common email formats

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

Examples:user@example.comtest.name+tag@domain.co.uk

Email (RFC 5322)

Strict RFC 5322 compliant (complex)

(?:[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*|"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])*")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\])

Examples:complex+tag@sub.domain.com

Phone Numbers

US Phone

US format with optional separators

^$?([0-9]{3})$?[-. ]?([0-9]{3})[-. ]?([0-9]{4})$

Examples:(123) 456-7890123-456-78901234567890

International Phone

E.164 international format

^\+?[1-9]\d{1,14}$

Examples:+14155552671+442071234567

URLs & Web

URL (HTTP/HTTPS)

HTTP/HTTPS URLs with query params

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

Examples:https://example.com/path?q=valuehttp://sub.domain.co.uk

Domain Name

Valid domain names

^(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\.)+[a-zA-Z]{2,}$

Examples:example.comsub.domain.co.uk

URL Slug

URL-friendly slugs

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

Examples:hello-worldmy-blog-post-123

Network

IPv4 Address

Valid IPv4 with range validation

^(?:(?: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]?)$

Examples:192.168.1.110.0.0.255

IPv6 Address

Full IPv6 format

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

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

MAC Address

Network MAC address

^([0-9A-Fa-f]{2}[:-]){5}([0-9A-Fa-f]{2})$

Examples:00:1A:2B:3C:4D:5E00-1A-2B-3C-4D-5E

Date & Time

Date (YYYY-MM-DD)

ISO 8601 date format

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

Examples:2024-12-252023-01-01

Date (MM/DD/YYYY)

US date format

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

Examples:12/25/202401/01/2023

Time (24-hour)

24-hour time with optional seconds

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

Examples:14:3023:59:59

ISO 8601 DateTime

Full ISO 8601 datetime

^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(?:\.\d+)?(?:Z|[+-]\d{2}:\d{2})?$

Examples:2024-12-25T14:30:00Z2024-12-25T14:30:00+05:30

Financial

Credit Card (All)

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})$

Examples:41111111111111115500000000000004

Currency Amount

US currency format

^\$?\d{1,3}(?:,\d{3})*(?:\.\d{2})?$

Examples:$1,234.561234.56$100

Security

Strong Password

Min 8 chars, upper, lower, digit, special

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

Examples:SecureP@ss1MyP@ssw0rd!

UUID v4

Version 4 UUID format

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

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

MD5 Hash

32-character hex MD5

^[a-fA-F0-9]{32}$

Examples:d41d8cd98f00b204e9800998ecf8427e

SHA-256 Hash

64-character hex SHA-256

^[a-fA-F0-9]{64}$

Examples:e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855

Code & Identifiers

Hex Color

3 or 6 digit hex color

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

Examples:#FFF#336699ff5733

RGB Color

RGB color function

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

Examples:rgb(255, 128, 0)rgb(0,0,0)

HTML Tag

Basic HTML tag matching

<([a-z]+)([^<]+)*(?:>(.*)<\/\1>|\s+\/>)

Examples:<div>content</div><br />

Semantic Version

SemVer 2.0 compliant

^(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-]+)*))?$

Examples:1.0.02.1.3-beta.11.2.3+build.456

Text

Alphanumeric Only

Letters and numbers only

^[a-zA-Z0-9]+$

Examples:Hello123ABC

Username

3-16 chars, letters, numbers, underscore

^[a-zA-Z0-9_]{3,16}$

Examples:john_doeuser123

No Special Characters

Alphanumeric with spaces

^[a-zA-Z0-9 ]+$

Examples:Hello WorldTest 123

Contains Only Letters

Latin letters only

^[a-zA-Z]+$

Examples:HelloWorld

💡 Tips for Using These Patterns

Test thoroughly: These patterns cover common cases but may need adjustment for edge cases in your specific application.
Consider performance: Complex patterns with many alternations or lookarounds can be slow on large inputs.
Escape in strings: When using in JavaScript/Python strings, you may need to double-escape backslashes (\\\\d → \\d).
Add flags as needed: Use /i for case-insensitive, /g for global matching.