Apple·Software Engineer·Onsite - System Design / Architecture
Apr 2026
Apple system design round for a software engineer role. One question, pretty focused, but it had enough layers to keep me busy for the whole session.
- Design a high-throughput service that accepts a positive integer and determines whether repeatedly replacing it with the sum of its squared digits eventually reaches 1. The service needs to handle billions of requests efficiently, with low latency and minimal redundant computation.
“I went straight to caching and that was the right instinct, but I fumbled explaining why the cache stays small.” The rest of the author's notes on Software Engineer interview at Apple, Onsite - System Design / Architecture round, covers how they worked through the question, what the panel pushed back on, and what they would do differently.
View Post