Meta System Design Interview Questions

You may have prepared by memorizing distributed systems trivia, and this round will not reward that. This section covers the actual prompt shapes, which sit closer to product engineering than to infrastructure. The recurring pattern is a consumer-scale feature you already use, handed to you as an open problem.

• Design a news feed. Ranking, fanout on write versus fanout on read, and what happens for accounts with millions of followers.
• Design a messaging or chat system. Delivery guarantees, ordering, presence, and offline sync across devices.
• Design a notification system. Deduplication, batching, per-user rate limits, and delivery across push, email, and in-app.
• Design nearby friends or a location feature. Geospatial indexing, update frequency, and the privacy model.
• Design a search or trending component. Indexing freshness against query latency.

Some loops split this into a product architecture variant that stays close to user-facing behavior. Ask your recruiter which one you are getting, because the preparation differs.

The failure mode is drawing boxes in minute two. A workable split: clarify requirements and scope, sketch the API and data model, draw the high-level architecture, then go deep where the interviewer points.

• Requirements first. Which users, which platforms, read-heavy or write-heavy, and what you are explicitly not building.
• Numbers next. Rough daily actives, request rates, and payload sizes, so later trade-offs have something to stand on.
• Data model before diagrams. What an entity looks like and how it is queried usually decides the architecture.
• One deep dive. Expect to be steered into a single component and asked how it fails.

State your assumptions out loud. An interviewer who disagrees with an assumption will correct it, which is free information; an unstated assumption just looks like a gap.

Average answers describe a correct architecture. Strong answers name the trade-off they accepted and the failure they are willing to tolerate. Saying "I am picking fanout on write because reads dominate here, and I am accepting slow writes for celebrity accounts, which I would handle with a separate pull path" does more than a perfect diagram.

Consider a backend engineer interviewing for a senior role. She is asked to design a notification system and spends the first six minutes only on requirements: whether a user can get two notifications for one event, whether ordering matters, what the retention window is. The interviewer later says the deduplication discussion was the deciding part of the round, and she never got past a single-page diagram.

Rehearsing this narration is the hard part alone at a desk. You can run design prompts against an AI interviewer on the /mock-interview page and get used to talking while you think.

On a spoken video round, SubcueAI transcribes the interviewer's question and surfaces a suggested structure on your side, in the desktop overlay on macOS and Windows or in the Chromium browser extension side panel. No meeting bot joins the call, and nothing is injected into the meeting page. For a design round the realistic value is a checklist you keep forgetting under pressure, such as the capacity estimate or the failure mode, rather than an answer you read aloud.

The limits are firm. Design rounds usually run on a shared whiteboard tool with your screen shared, and anything on your screen is visible to the panel. Reading a generated answer also collapses immediately, because the interviewer's next question is "why not the other approach?". Related loops for other employers sit in the company interviews topic.