Blog

Deep dives into backend engineering concepts, from HTTP internals to distributed systems.

Backend Fundamentals8 min read

Why Your POST Request Fails but GET Works — CORS & Preflight Explained

A deep dive into CORS, preflight requests, and why browsers block your API calls. Includes a visual flow diagram of how the OPTIONS preflight mechanism works.

CORSHTTPAPI
Mar 31, 2026
Networking10 min read

What Happens in the Split Second After Your VPN Disconnects

A layer-by-layer breakdown of what happens when a VPN drops — tunnel teardown, routing table rewrites, TCP connection death, DNS leaks, and why QUIC survives it all.

VPNTCPDNS
Mar 31, 2026