Design a Content Delivery for Instacart
Last updated: August 16, 2025
Quick Overview
Design a fault-tolerant content delivery system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Instacart
System Design
Software Engineer
Instacart
August 16, 2025Software Engineer
Technical Screen
System Design
Medium
31
13
3,666 solved
Design a fault-tolerant content delivery system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
System design interviews at Instacart 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
Database selection and data modeling
Failure handling and fault tolerance
Security and authentication
High-level architecture and component design
Requirements gathering and capacity estimation
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 implement rate limiting to protect the system?
- How do you ensure data consistency across multiple services?
- What would the deployment pipeline look like for this system?
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Requirements
Functional Requirements
- Content Delivery: The system must deliver product images, descriptions, and promotional content to users in real-time as they browse items on Instacart.
- **User Au...
Capacity Estimation
Back-of-Envelope Calculations
- User Base: Assume Instacart has 20 million active users.
- Peak Load: During peak hours (assumed to be 3 hours a day), let's estimate 10% of users are act...
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