Proxy vs Reverse Proxy vs Load Balancer vs API Gateway — One Box, 4 Hats
Proxy, reverse proxy, load balancer, API gateway. Four intimidating names you keep hitting in system design — and every explanation hands you a table of "5 differences" that only makes it worse.
Here's the thing they bury: these aren't four different technologies. They're the SAME box — a proxy, a middleman on the request path — standing on a different side, doing a different job. One box, wearing different hats. Learn what a middleman actually does, then three tiny questions that let you name any of them on sight.
Chapters:
0:00 4 scary names, 1 box
0:52 What a proxy actually is (receive · forward · return)
2:45 Forward vs reverse — the mirror
4:12 The reverse proxy's jobs (and where "load balancer" comes from)
6:17 The API gateway
7:53 Recap: Side · Spread · Speak
What you'll learn:
• A proxy is just a middleman for a request: it receives, opens its OWN connection onward, and relays the response back — which is exactly why the server sees the proxy's address, not yours (that's what X-Forwarded-For is for).
• Forward vs reverse is only a question of SIDE: a forward proxy is your agent facing out; a reverse proxy is the servers' agent facing in. Same box, mirrored.
• "Load balancer" is just a reverse proxy whose job is spreading traffic across many servers. An API gateway is a reverse proxy that also speaks API — auth once, rate limits, routing, and combining answers.
• Roles, not products: one real piece of software (like nginx) can be all of these at once. Ask "what job is this box doing here?", not "which of the four is it?".
Three questions to name any of them: Side · Spread · Speak.
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