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

Senior

Jul 2026

Summary

Day 2 of the Meta onsite, one round covering system design plus behavioral. The design topic was Chess, which is a known Meta question so I wasn't totally blindsided, but knowing it's common and actually doing it well are two different things.

Questions Asked (1)

Design a system to support an online Chess game.

System DesignData ModelingTechnical Trade-offs

Author's notes

I knew this question floats around for Meta so I had a rough outline in my head going in.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and scale, then design the core data model and game flow, and finally address scalability, real-time communication, and trade-offs. Focus on the unique aspects of chess (e.g., move validation, game state) while applying standard system design principles.

Pro tip: Demonstrate deep understanding of chess-specific challenges like move validation and game state synchronization, and discuss how to handle cheating detection and matchmaking. Also, consider using a chess engine for validation and analysis.

1. Clarify Requirements and Scope

Ask questions to understand functional and non-functional requirements: number of players, concurrent games, real-time vs turn-based, matchmaking, rating system, persistence, etc.

2. Design Core Data Model and Game Logic

Define how to represent the board, pieces, moves, and game state. Discuss move validation, check/checkmate detection, and game history.

3. Design System Architecture and APIs

Outline the high-level components: client, API gateway, game service, matchmaking service, database, cache, and real-time communication (WebSockets). Define key APIs for creating games, making moves, and retrieving game state.

4. Address Scalability, Reliability, and Trade-offs

Discuss how to scale horizontally, handle failures, ensure low latency, and choose between consistency and availability. Consider trade-offs in data storage (SQL vs NoSQL), real-time updates (WebSockets vs polling), and move validation (client vs server).

5. Discuss Advanced Features and Edge Cases

Cover matchmaking algorithms, rating systems (e.g., Elo), cheating detection, game analysis, and spectator mode. Also, consider handling disconnections and reconnections.

Key Points to Mention

Use of WebSockets for real-time move updates and notifications.
Server-side move validation to prevent cheating and ensure game integrity.
Data model for game state: board representation (e.g., FEN), move history (PGN), and player information.
Scalability considerations: sharding by game ID, caching popular games, and using a message queue for move processing.
Matchmaking service using Elo rating and waiting pool.
Trade-offs between consistency and latency: e.g., using optimistic UI updates with server reconciliation.

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