URL Validation Regex (Simple)

A simple regex pattern for validating URLs with optional protocol, domain, TLD, and path components.

Pattern Breakdown

^(https?:\/\/)?([\da-z\.-]+)\.([a-z\.]{2,6})([\/\w \.-]*)*\/?$

Components

Character Classes

• https? - http or https (s is optional)
• \/ - Literal forward slash (escaped)
• [\da-z\.-] - Domain characters: digits, lowercase letters, dots, hyphens
• [a-z\.] - TLD characters: lowercase letters and dots
• [\/\w \.-] - Path characters: forward slash, word chars, spaces, dots, hyphens
• ? - Quantifier: zero or one occurrence (optional)
• + - Quantifier: one or more occurrences
• * - Quantifier: zero or more occurrences
• {2,6} - Quantifier: between 2 and 6 occurrences

Examples

Valid:

• https://example.com
• http://www.example.com
• example.com
• subdomain.example.org
• example.co.uk
• example.com/path/to/page
• example.com/path/to/page/

Invalid:

• example (missing TLD)
• example.c (TLD too short)
• EXAMPLE.COM (uppercase not allowed)
• http://example (missing TLD)
• https://example..com (double dot)

Implementation

JavaScript

const urlRegex = /^(https?:\/\/)?([\da-z\.-]+)\.([a-z\.]{2,6})([\/\w \.-]*)*\/?$/;
urlRegex.test('https://example.com'); // true
urlRegex.test('example.com/path'); // true
urlRegex.test('http://subdomain.example.org'); // true
urlRegex.test('example'); // false (missing TLD)

Python

import re
url_regex = r'^(https?:\/\/)?([\da-z\.-]+)\.([a-z\.]{2,6})([\/\w \.-]*)*\/?$'
bool(re.match(url_regex, 'https://example.com'))  # True
bool(re.match(url_regex, 'example.com/path'))  # True
bool(re.match(url_regex, 'example'))  # False (missing TLD)

Go

urlRegex := regexp.MustCompile(`^(https?:\/\/)?([\da-z\.-]+)\.([a-z\.]{2,6})([\/\w \.-]*)*\/?$`)
urlRegex.MatchString("https://example.com") // true
urlRegex.MatchString("example.com/path") // true
urlRegex.MatchString("example") // false (missing TLD)

Limitations

1. Lowercase only: Only accepts lowercase letters in domain and TLD
2. No port numbers: Doesn't support :8080 port specification
3. No query strings: Doesn't validate query parameters (?key=value)
4. No fragments: Doesn't support URL fragments (#section)
5. No IPv4/IPv6: Doesn't validate IP addresses as hosts
6. Simple validation: Basic format check, not comprehensive URL validation

When to Use

• Simple URL format validation
• Client-side form validation
• Quick URL format checking
• When you need basic URL pattern matching
• Prototyping or early development

For production, consider:

• Using URL parsing libraries for comprehensive validation
• Supporting uppercase letters
• Adding port, query string, and fragment support
• Validating actual URL accessibility
• Using stricter patterns or validation libraries