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URL Validator - Check URL Format and Parse Components

URL Validator

Validate URL format and parse URL components

Enter a complete URL with protocol (http:// or https://)

About URL Validation

A URL (Uniform Resource Locator) is a reference to a web resource that specifies its location on a computer network and a mechanism for retrieving it. URLs are fundamental to how the web works, and proper URL validation is essential for web applications, APIs, and data processing systems. Understanding URL structure and validation helps prevent security vulnerabilities, improve user experience, and ensure data quality.

URL Structure

A complete URL consists of several components: 

https://user:password@www.example.com:8080/path/to/page?query=value&foo=bar#section

├─ Scheme: https
├─ User Info: user:password (optional, rarely used)
├─ Host: www.example.com
├─ Port: 8080 (optional, defaults: 80 for HTTP, 443 for HTTPS)
├─ Path: /path/to/page
├─ Query: query=value&foo=bar
└─ Fragment: section

URL Components Explained

  • Scheme (Protocol): Defines how to access the resource (http, https, ftp, mailto, etc.)
  • Domain (Host): The server address where the resource is located
  • Port: The network port to connect to (optional, has defaults)
  • Path: The specific location of the resource on the server
  • Query String: Key-value pairs for passing data to the server
  • Fragment (Hash): Points to a specific section within the resource

Common URL Schemes

Scheme Purpose Example
http Hypertext Transfer Protocol http://example.com
https Secure HTTP (with SSL/TLS) https://example.com
ftp File Transfer Protocol ftp://ftp.example.com
mailto Email address mailto:user@example.com
file Local file system file:///path/to/file

URL Encoding

Special characters in URLs must be encoded using percent-encoding (also called URL encoding):

Character Encoded Purpose
Space %20 or + Separates words in queries
& %26 Reserved for query parameter separator
= %3D Reserved for query key-value separator
# %23 Reserved for fragments
? %3F Reserved for query string start

Valid URL Examples

  • https://www.example.com - Simple HTTPS URL
  • https://example.com:8080/path - With custom port and path
  • https://example.com/search?q=test&page=1 - With query parameters
  • https://example.com/page#section - With fragment
  • http://192.168.1.1/admin - IP address as host
  • http://localhost:3000 - Local development server

Common URL Validation Errors

  • Missing scheme: URLs must start with a protocol (http://, https://)
  • Invalid characters: Some characters must be percent-encoded
  • Malformed domain: Domain names must follow DNS naming rules
  • Invalid port: Port numbers must be between 1 and 65535
  • Incorrect encoding: Special characters improperly encoded
  • Multiple question marks: Only one ? allowed to start query string

When to Use URL Validation

  • Form Validation: Ensure users enter valid URLs in web forms
  • API Development: Validate URL parameters and webhook URLs
  • Web Scraping: Verify URLs before making HTTP requests
  • Link Checkers: Validate URLs in content management systems
  • Configuration Files: Verify API endpoints and service URLs
  • Security: Prevent URL injection and SSRF attacks

Security Considerations

Security Warning: URL validation should include:
  • Whitelist allowed schemes (typically only http and https)
  • Prevent localhost and private IP addresses for user-submitted URLs
  • Validate against SSRF (Server-Side Request Forgery) attacks
  • Check for open redirects in URL parameters
  • Sanitize URLs before displaying or storing
  • Use HTTPS whenever possible for sensitive data

URL vs URI vs URN

Term Meaning Example
URI Uniform Resource Identifier (generic term) https://example.com/page or urn:isbn:0-486-27557-4
URL Uniform Resource Locator (specifies location) https://example.com/page
URN Uniform Resource Name (identifies by name) urn:isbn:0-486-27557-4

Best Practices

  • Always use HTTPS for production websites and APIs
  • Keep URLs short and readable when possible
  • Use hyphens (not underscores) in URL paths for SEO
  • Implement proper URL encoding for all user input
  • Validate URLs on both client and server side
  • Use canonical URLs to avoid duplicate content issues
  • Implement proper redirects (301/302) when URLs change
  • Consider internationalized domain names (IDN) for global audiences

SEO Considerations

  • Use descriptive, keyword-rich URLs
  • Keep URLs simple and easy to understand
  • Avoid excessive parameters and session IDs
  • Use lowercase letters consistently
  • Implement proper URL structure for site hierarchy
  • Use trailing slashes consistently

Additional Resources