Design Messaging Infrastructure for mobile apps
Last updated: May 18, 2026
Quick Overview
Design a scalable messaging system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Jump Trading
May 18, 202611
5
3,091 solved
Design a scalable messaging system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
System design interviews at Jump Trading typically last 45-60 minutes. You are expected to drive the conversation, starting from requirements gathering through to a detailed architecture. The interviewer will evaluate your ability to handle ambiguity and make practical engineering decisions.
What the Interviewer Expects
- Systematically gather requirements and estimate capacity (QPS, storage, bandwidth)
- Design a scalable architecture with clear component responsibilities
- Make well-reasoned database and caching decisions with trade-off analysis
- Address consistency vs availability trade-offs specific to the use case
- Discuss partitioning strategy, replication, and data modeling
- Cover failure handling, monitoring, and alerting strategies
Key Topics to Cover
How to Approach This
- Start by clarifying functional and non-functional requirements with the interviewer.
- Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
- Draw a high-level architecture first, then deep dive into 1-2 critical components.
- Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
- Address failure scenarios, monitoring, and how the system handles 10x traffic spikes.
Possible Follow-up Questions
- How would you handle a region-wide outage?
- What monitoring and alerting would you set up on day one?
- How would you handle a 10x increase in traffic overnight?
- How would you handle schema migrations with zero downtime?
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Requirements
Functional Requirements:
- Real-time Messaging: Users should be able to send and receive messages instantly with low latency.
- Group Messaging: Support for one-to-many messaging to allo...
Capacity Estimation
Assuming Jump Trading expects 10 million active users with each user sending an average of 5 messages per day:
- Total Messages per Day: 10,000,000 users * 5 messages = 50,000,000 messages/day. 2...
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