Design a car rental booking system
Company: Moveworks
Role: Software Engineer
Category: System Design
Difficulty: medium
Interview Round: Onsite
## System Design: Car Rental Booking System
Design an online car rental system (like Hertz/Avis) that allows users to search and book rental cars.
### Core user flows
1. **Search** available cars by:
- pickup location
- pickup date/time and return date/time
- car class (economy/SUV/etc.) and optional filters (price, seats)
2. **Quote** pricing (base rate + fees + taxes).
3. **Book** a car.
4. **Cancel / modify** a reservation.
### Requirements
- Prevent **double-booking** of the same car for overlapping time ranges.
- Handle high read traffic for search and spikes during promotions.
- Provide good UX: quick search results and reliable booking confirmation.
### Assumptions (you may choose reasonable defaults)
- Fleet is organized by location; each car belongs to one location.
- A reservation is a time interval \([start, end)\) with timezone-aware timestamps.
### Deliverables
- APIs (high level)
- Data model
- High-level architecture (services, storage, caching)
- Concurrency/control approach (database locks / optimistic concurrency / distributed locks)
- Scaling and reliability considerations
Quick Answer: This question evaluates understanding of system design competencies including scalability, data modeling, API design, concurrency control, transactional integrity, and caching for a time-based booking domain.