HTTP/1.1, HTTP/2 and HTTP/3 Deep Dive
Methods, headers, status codes, keep-alive, chunked encoding, multiplexing, QUIC — the protocol backend developers debug every day.
Computer Networking
Network protocols behind every API call: HTTP, TCP, DNS, WebSocket and CORS.
All 3 tutorials
TCP/IP Essentials for Backend Engineers
Three-way handshake,滑动窗口, TIME_WAIT, CLOSE_WAIT, half-open connections and the tools to see them all.
CORS: Cross-Origin Requests Explained
What CORS actually is (a browser relaxation, not server security), preflight, credentialed requests, and the config that finally makes it work.