Design a multi-tenant Chat System
Last updated: October 20, 2025
Quick Overview
Design a multi-tenant chat system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Rippling
System Design
Software Engineer
Rippling
October 20, 2025Software Engineer
System Design Round
System Design
Medium
2
10
157 solved
Design a multi-tenant chat system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
System design interviews at Rippling 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
Load balancing and horizontal scaling
Security and authentication
API design and rate limiting
Caching strategies (local, distributed, CDN)
Consistency models and replication
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 migrate from a monolithic to a microservices architecture?
- How would you handle a 10x increase in traffic overnight?
- How do you ensure data consistency across multiple services?
- How would you handle a region-wide outage?
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Requirements
Functional Requirements:
- Multi-Tenancy: The system must support multiple organizations (tenants) with data isolation.
- Real-time Messaging: Users should be able to send and receive me...
Capacity Estimation
Back-of-Envelope Calculations:
- Concurrent Users: Assume 1 million total users, with an average of 10% active (100,000 users).
- Messages per User: Assume an average of 5 messages per use...
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