Design a multi-tenant Notification System
Last updated: January 29, 2026
Quick Overview
Design a multi-tenant notification system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
CrowdStrike
System Design
Software Engineer
CrowdStrike
January 29, 2026Software Engineer
Onsite
System Design
Medium
29
8
2,241 solved
Design a multi-tenant notification system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
CrowdStrike asks this during the Onsite to assess your architectural thinking. They want to see how you decompose a complex problem, choose appropriate technologies, and reason about failure modes. Strong candidates proactively discuss monitoring, alerting, and operational concerns.
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
High-level architecture and component design
Load balancing and horizontal scaling
Caching strategies (local, distributed, CDN)
Monitoring, logging, and alerting
Database selection and data modeling
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 10x increase in traffic overnight?
- How do you ensure data consistency across multiple services?
- How would you handle schema migrations with zero downtime?
- What happens if one of your database nodes goes down?
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Requirements
- Functional Requirements:
- Support multi-tenancy to allow different clients to manage their notifications independently.
- Ability to send notifications via multiple channels (email, S...
Capacity Estimation
- Assumptions:
- Expected daily notifications: 10 million.
- Average notifications per tenant: 500.
- Peak hours: 10% of total daily messages (1 million messages/hour).
- **Cal...
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