Nooks·Software Engineer·Onsite - System Design / Architecture·Senior

SeniorPrefer not to say

Jun 2026

Summary

System design round at Nooks for a software engineer role, basically a Twitter clone question that sounds straightforward until you get into feed generation and celebrity accounts and realize there's a lot of ground to cover.

Questions Asked (1)

Design a simplified Twitter-like system that supports user accounts, following, posting short text, a profile timeline, and a home feed showing posts from followed accounts.

System DesignTechnical Trade-offsData Modeling

Author's notes

I started with requirements and APIs which felt safe, but the interviewer kept pushing toward the feed generation part and I hadn't fully committed to a strategy yet.

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AI HintsAI Generated

Suggested Approach

Start by clarifying functional and non-functional requirements, then estimate scale to inform design choices. Propose a high-level architecture with core components (API, services, data stores), and dive into data modeling and feed generation strategies, discussing trade-offs between fan-out on write vs. read. Conclude by addressing scalability, availability, and potential bottlenecks.

Pro tip: Explicitly discuss the trade-offs between push (fan-out on write) and pull (fan-out on read) models for the home feed, and suggest a hybrid approach for handling celebrity users. This shows you understand real-world complexities beyond basic design.

1. Clarify Requirements and Scale

Ask questions to define functional requirements (e.g., user accounts, following, posting, timelines) and non-functional requirements (e.g., latency, availability, consistency). Estimate scale (e.g., daily active users, posts per user, read/write ratio) to guide design decisions.

2. High-Level Architecture

Outline the main components: client, API gateway, user service, post service, timeline service, and data stores (SQL/NoSQL, cache, message queue). Explain how they interact to support the required features.

3. Data Modeling and Storage

Design schemas for users, follows, and posts. Choose appropriate databases (e.g., relational for user/follow, wide-column for posts) and discuss indexing for efficient queries (e.g., user timeline, home feed).

4. Feed Generation Strategy

Compare fan-out on write vs. fan-out on read for home feed. Discuss trade-offs (latency, storage, complexity) and propose a hybrid approach (e.g., push for normal users, pull for celebrities) to balance load.

5. Scalability and Trade-offs

Address scaling bottlenecks (e.g., hot users, storage growth) with techniques like sharding, caching, and asynchronous processing. Discuss consistency vs. availability trade-offs and how to handle failures.

Key Points to Mention

Fan-out on write vs. fan-out on read for home feed generation, including hybrid approaches for celebrity users.
Data modeling: separate tables/collections for users, follows, and posts; use of graph or relational DB for social graph.
Caching strategies (e.g., Redis) for user timelines and home feeds to reduce latency.
Sharding and partitioning strategies for posts and social graph to handle scale.
Asynchronous processing with message queues for feed updates and notifications.
Trade-offs between consistency and availability (CAP theorem) and how to choose based on requirements.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.