REST — Part 3: Advanced Patterns & Interview Q&A

maang.io System Design Series

What is this?

You know the library now — addressed resources, standard verbs, status codes, caching. This part is the oral exam: a mentor sitting across the table, asking the questions that actually come up when a company is deciding whether you reason like a senior engineer. We'll go through them the way a good mock interview goes — first decode what they're really asking, then build the answer, then land the senior line that makes the interviewer nod.

The one-line idea: at the senior level, REST questions aren't "what's a PUT" — they're "when does REST stop being the right tool, and what do you reach for instead?" Your job is to show you know REST's edges as well as its center.

A quick anti-pattern warm-up before the questions, because spotting these is half the battle.