Design a Ticketmaster-like ticketing system
Company: Microsoft
Role: Software Engineer
Category: System Design
Difficulty: medium
Interview Round: Onsite
## System Design: Online ticketing platform (Ticketmaster-like)
Design a system that sells tickets for events (concerts/sports) with **seat selection**.
### Core user flows
1. Browse/search events.
2. View event details and seat map.
3. Select 1..k seats.
4. Temporarily **hold/reserve** selected seats.
5. Checkout and pay.
6. Receive confirmation and ticket(s) (e.g., QR code).
### Requirements
#### Functional
- Support both **assigned seating** (seat map) and optionally **general admission** (quantity).
- Prevent double-selling the same seat.
- Seat holds expire (e.g., 5–10 minutes).
- Users can cancel; system releases seats.
- Integrate with external payment provider.
#### Non-functional
- Very high burst traffic at on-sale time (hundreds of thousands to millions of users).
- Low latency for seat map/availability.
- Strong correctness: no overselling.
- Fairness controls (queues/waiting room), anti-bot protections.
- Observability and auditability (who held/bought what).
### Deliverables
Explain:
- APIs
- Data model
- High-level architecture
- Seat locking/holding strategy and consistency
- Scaling, caching, and failure handling
- Anti-bot and fairness mechanisms
Quick Answer: This question evaluates a candidate's competency in designing scalable, consistent online ticketing platforms, testing knowledge of distributed systems, concurrency control, data modeling, API design, caching, payment integration, anti-bot measures, and observability.