Question library
Questions from real interviews. Drill any of them by voice in a couple of minutes, with an interviewer, a score and feedback.
Let's say you need to build a REST API for a simple notes service. What endpoints would you create, and what would they look like?JuniorA client sends a POST request to create a payment, the response never arrives because of a timeout, and the client retries the request. How do you make sure the money isn't charged twice?Mid-levelHow would you implement pagination in a feed API with millions of records where new ones are constantly being added? What options do you know, and how do they differ?Mid-levelDesign a rate limiter for a public API: for example, no more than 100 requests per minute per API key. The service runs on several instances.Mid-levelA client calls your create-payment endpoint, the response is lost to a timeout, and the client retries the request. How would you design the API so the money isn't charged twice?SeniorYou have a public API used by hundreds of external integrations, and you need to change the format of a key resource in a backward-incompatible way. How would you go about it?SeniorКак вы выстроите защиту API, через которое мобильное приложение получает данные о счетах клиента, — на всём пути от приложения до базы?SeniorYour team is writing an internal Java library that twenty other teams will use. How would you design its API so it can evolve without breaking clients?Senior