python validate url
django url validation regex (source):
import re
regex = re.compile(
r'^(?:http|ftp)s?://' # http:// or https://
r'(?:(?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?.)+(?:[A-Z]{2,6}.?|[A-Z0-9-]{2,}.?)|' #domain...
r'localhost|' #localhost...
r'd{1,3}.d{1,3}.d{1,3}.d{1,3})' # ...or ip
r'(?::d+)?' # optional port
r'(?:/?|[/?]S+)$', re.IGNORECASE)
print(re.match(regex, "http://www.example.com") is not None) # True
print(re.match(regex, "example.com") is not None) # False