Netflix·Software Engineer·Onsite - System Design / Architecture
May 2026
Netflix system design round for a software engineer role. The main problem was building a key-value cache with per-key TTL, and the conversation went pretty deep into eviction, concurrency, and scaling. Left feeling okay about it but not great.
- Design a key-value cache that supports setting a value with a per-key TTL, retrieving a value only if it hasn't expired, and deleting a key. Walk through your eviction strategy, thread-safety considerations, and how this scales.
“Started with the basics: a hashmap storing value plus expiry timestamp, check on get and return null if stale.” The rest of the author's notes on Software Engineer interview at Netflix, Onsite - System Design / Architecture round, covers how they worked through the question, what the panel pushed back on, and what they would do differently.
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