For urllib: "urllib.request module uses HTTP/1.1 and includes a "Connection:close" header in its HTTP requests"[1] [1] https://github.com/python/cpython/b

For urllib: "urllib.request module uses HTTP/1.1 and includes a "Connection:close" header in its HTTP requests"[1] [1] https://github.com/python/cpython/blob/3.10/Lib/urllib/request.py#L147 https://github.com/python/cpython/blob/3.10/Lib/urllib/reque... You seem to be correct about urllib3 and requests, I was wrong there...though they do have the dependency on urllib.