10 Regex Patterns Every Developer Should Know

Table of Contents

• 1. Email Address
• 2. URL
• 3. Phone Number
• 4. Strong Password
• 5. IPv4 Address
• 6. Date (YYYY-MM-DD)
• 7. URL Slug
• 8. Hex Color
• 9. UUID
• 10. Credit Card

1. Email Address

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

Matches: user@example.com, test.name+tag@sub.domain.co.uk

2. URL

/^https?:\/\/[^\s/$.?#].[^\s]*$/i

For strict URL parsing, use new URL(str) and catch the error instead.

3. Phone Number (US)

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

Matches: (555) 123-4567, 555.123.4567, +15551234567

4. Strong Password

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

Requires: 8+ chars, one lowercase, one uppercase, one digit, one special character.

5. IPv4 Address

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

6. Date (YYYY-MM-DD)

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

7. URL Slug

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

Matches: hello-world, my-post-2025

8. Hex Color

/^#([0-9a-f]{3}|[0-9a-f]{6}|[0-9a-f]{8})$/i

Matches: #fff, #ff5733, #ff573380 (with alpha)

9. UUID (v4)

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

10. Credit Card (basic)

/^(?:4\d{12}(?:\d{3})?|5[1-5]\d{14}|3[47]\d{13})$/

Detects Visa (4), Mastercard (51–55), Amex (34/37). Use Stripe in production.

Test all patterns with the Regex Tester.