Interview Q&A / System Design
System Design interview questions
Caching, scaling, databases and classic design problems for beginners.
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- What is the difference between REST and GraphQL?
REST exposes many fixed endpoints that each return a set shape of data. GraphQL exposes one endpoint where the client asks for exactly the fields it needs, which avoids over-fetching but makes caching and rate limiting harder.
BeginnerQuick answer1 min read - Which HTTP methods are safe and which are idempotent?
Safe methods (GET, HEAD, OPTIONS) don't change server state. Idempotent methods (GET, PUT, DELETE and the safe ones) give the same result when repeated. POST is neither, and PATCH is not guaranteed idempotent.
BeginnerQuick answer1 min read - Which HTTP status codes should every API developer know?
Know the families: 2xx success (200, 201, 204), 3xx redirect (301, 304), 4xx client error (400, 401, 403, 404, 409, 429), 5xx server error (500, 502, 503, 504). The code tells clients whether retrying can help.
BeginnerQuick answer1 min read