The Regex Reference You Actually Need

Rather than another tutorial, this is a practical reference of patterns you'll actually use — with clear explanations of how each part works.

1. Email Address

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

Validates standard email format. Not RFC-compliant (there is no perfect email regex), but catches typos and common mistakes.

2. URL

/^https?:\/\/[\w\-]+(\.[\w\-]+)+[/#?=$]*/

Matches http and https URLs with a hostname and optional path.

3. IPv4 Address

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

Validates each octet as 0–255, preventing invalid IPs like 256.0.0.1.

4. Phone Number (US)

/^\(?\d{3}\)?[-.\s]?\d{3}[-.\s]?\d{4}$/

Matches (555) 123-4567, 555-123-4567, 5551234567, etc.

5. Hex Color Code

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

Matches #FFF, #ffffff, #000, with or without the # prefix.

6. Date (YYYY-MM-DD)

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

Validates year, month (01–12), and day (01–31) with proper month bounds.

7. Time (HH:MM or HH:MM:SS)

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

Matches 00:00 to 23:59, with optional seconds.

8. Username

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

Alphanumeric + underscore/hyphen, 3–16 characters.

9. Strong Password

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

Requires: lowercase, uppercase, digit, special char, min 8 chars.

10. Credit Card (basic)

/^\d{4}[- ]?\d{4}[- ]?\d{4}[- ]?\d{4}$/

Matches Visa, Mastercard format. Use a payment library for real validation.

11. Slug / URL-friendly string

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

Lowercase letters, numbers, single hyphens between words. No leading/trailing hyphens.

12. HTML Tag

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

Matches opening tags with content and closing tags, or self-closing tags.

13. Comma-Separated Numbers

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

Matches 1,000, 1,000,000 but not 10,00 or 1000,000.

14. UUID

/^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-
  [0-9a-f]{4}-[0-9a-f]{12}$/i

Matches standard UUID format (v4 or any version).

15. File Extension

/\.(jpg|jpeg|png|gif|webp)$/i

Extracts image file extensions from filenames.

Test Your Regexes

Use our Regex Tester to validate patterns against test strings — with real-time highlighting of matches and capture groups.