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Validate URL

Zero-dependency Python snippets for validating URLs using the standard library.

4 snippets available in this sub-category.

Simple

Check if URL has valid scheme and netloc

url validate scheme netloc web

Check if URL has valid scheme and netloc

from urllib.parse import urlparse

def is_valid_url(url):
    """Return True if URL has a valid scheme and netloc."""
    parsed = urlparse(url)
    return all([parsed.scheme in ('http', 'https', 'ftp'), parsed.netloc])

# Example usage
print(is_valid_url('https://example.com'))  # True
print(is_valid_url('ftp://ftp.example.com'))  # True
print(is_valid_url('example.com'))  # False

Notes

  • Only checks for presence of scheme and netloc
  • Does not check if domain actually exists

Validate URL with regex (basic)

url validate regex pattern web

Validate URL with regex (basic)

import re

def is_valid_url_regex(url):
    """Basic regex validation for HTTP/HTTPS URLs."""
    pattern = re.compile(r'^https?://[\w.-]+(?:\.[\w\.-]+)+[/\w\.-]*$')
    return bool(pattern.match(url))

# Example usage
print(is_valid_url_regex('https://example.com/page'))  # True
print(is_valid_url_regex('http://localhost:8000'))  # True
print(is_valid_url_regex('ftp://example.com'))  # False

Notes

  • Regex can be customized for stricter validation
  • Does not check for reachability

Complex

Validate URL with reserved domains and invalid characters

url validate strict reserved invalid web

Strict URL validation (reserved domains, invalid chars)

from urllib.parse import urlparse
import re

def is_valid_url_strict(url):
    """Strict URL validation: scheme, netloc, no reserved domains, no spaces."""
    parsed = urlparse(url)
    if parsed.scheme not in ('http', 'https', 'ftp'):
        return False
    if not parsed.netloc or ' ' in url:
        return False
    # Disallow reserved/test domains
    reserved = ('.test', '.example', '.invalid', '.localhost')
    if any(parsed.netloc.endswith(r) for r in reserved):
        return False
    # Basic character check
    if not re.match(r'^[\w\.-]+$', parsed.netloc.replace(':', '')):
        return False
    return True

# Example usage
print(is_valid_url_strict('https://example.com'))  # True
print(is_valid_url_strict('https://localhost'))  # False
print(is_valid_url_strict('https://example .com'))  # False

Notes

  • Disallows reserved/test domains and spaces
  • Checks for valid characters in netloc

Edge Cases

Validate missing scheme, empty, or malformed URLs

url validate edge-case empty malformed web

Validate missing scheme, empty, or malformed URLs

def is_valid_url(url):
    # Function is defined in one of the above code block
    pass


print(is_valid_url(''))  # False
print(is_valid_url('not a url'))  # False
print(is_valid_url('http:///path'))  # False

Notes

  • Returns False for empty or malformed URLs
  • Does not check for DNS or server reachability

🔗 Cross-References

🏷️ Tags

url, validate, scheme, netloc, regex, strict, reserved, edge-case, web

📝 Notes

  • Use urlparse for basic validation, regex for stricter checks
  • For production, consider using validators or DNS checks
  • Always sanitize and validate user input URLs