Design Ride Matching Infrastructure for mobile apps

Last updated: September 11, 2025

Quick Overview

Design a distributed ride matching system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.

Plaid
System Design
Software Engineer
Plaid
September 11, 2025
Software Engineer
Onsite
System Design
Medium

114

10

2,417 solved


Design a distributed ride matching system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.

Plaid 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
Load balancing and horizontal scaling
Requirements gathering and capacity estimation
Security and authentication
High-level architecture and component design
Consistency models and replication
How to Approach This
  1. Start by clarifying functional and non-functional requirements with the interviewer.
  2. Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
  3. Draw a high-level architecture first, then deep dive into 1-2 critical components.
  4. Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
  5. Address failure scenarios, monitoring, and how the system handles 10x traffic spikes.
Possible Follow-up Questions
  • How would you optimize costs as the system scales?
  • What happens if one of your database nodes goes down?
  • How would you handle schema migrations with zero downtime?
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Sample Answer
Requirements Clarification

Before diving into the architecture, clarify the scope with the interviewer. For Ride Matching Infrastructure for mobile apps, key functional requirem...

Capacity Estimation

Estimate the scale to drive design decisions. Assume 100M DAU with an average of 10 actions per user per day = 1B requests/day ~ 12K QPS average, ~36K...


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