import re

# This regex validates common HTTP/HTTPS URLs with a domain and optional path.
# It does not cover all edge cases (e.g., IP addresses as host, very specific characters in path).
url_pattern = r"^(https?://)?([a-zA-Z0-9-]+\.)+[a-zA-Z]{2,}(/[^\s]*)?$"

def is_valid_url(url):
    return bool(re.match(url_pattern, url))

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