Asana·Software Engineer·Onsite - System Design / Architecture·Intermediate

Intermediate

Apr 2026

Summary

Went through a system design round at Asana for a software engineer role. The prompt was designing a collaborative todo list, which sounds deceptively simple but has a lot of real-time sync and concurrency stuff hiding underneath.

Questions Asked (1)

Design a collaborative todo list application that supports multiple users working on the same list in real time.

System DesignData ModelingTechnical Trade-offs

Author's notes

My first instinct was to just sketch out a basic CRUD API and call it a day, which would have been embarrassing.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements: scale, consistency needs, and offline support. Then propose a high-level architecture with real-time sync, conflict resolution, and data model, and discuss trade-offs between approaches like OT vs CRDT.

Pro tip: Demonstrate awareness of Asana's existing real-time infrastructure and emphasize the importance of conflict resolution strategies like operational transformation or CRDTs, showing you understand the complexities of collaborative editing.

1. Clarify Requirements

Ask about expected number of concurrent users, list size, offline support, and consistency requirements to scope the problem.

2. High-Level Architecture

Outline components: clients, real-time sync server, persistence layer, and optional pub/sub for scalability.

3. Data Model & Sync Protocol

Define data structures for lists, tasks, and operations. Choose a sync protocol (WebSocket) and conflict resolution method (OT or CRDT).

4. Scalability & Reliability

Discuss scaling the sync server (sharding, load balancing), handling failures, and ensuring data durability.

5. Trade-offs & Alternatives

Compare OT vs CRDT, centralized vs decentralized, and discuss trade-offs in latency, complexity, and consistency.

Key Points to Mention

Real-time communication using WebSockets or Server-Sent Events
Conflict resolution: Operational Transformation (OT) vs Conflict-Free Replicated Data Types (CRDTs)
Data consistency models: eventual vs strong consistency
Scalability considerations: sharding, load balancing, and pub/sub (e.g., Redis, Kafka)
Offline support and synchronization upon reconnection
Data model design: lists, tasks, users, permissions, and operation logs

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