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Design a Concert Ticket Booking System - Low-Level Design | OneNoughtOne

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Design a Concert Ticket Booking System

Intermediate

Design an object-oriented concert ticket booking system that manages venues with sectioned seat maps (VIP, Premium, Regular, Standing), event scheduling with per-type pricing, a temporary seat-hold mechanism with configurable timeout, payment processing, and booking confirmation.

Seats transition through AVAILABLE → HELD → BOOKED (or back to AVAILABLE on expiry/cancellation). Bookings follow a lifecycle: PENDING (seats held) → CONFIRMED (payment received) or EXPIRED/CANCELLED. The system supports event cancellation with bulk refunds and a background sweep to expire stale holds.

Core Use Cases

Create venues with seat maps

Schedule events

Create events at a venue with per-type pricing and sales status

Search events

Search by name, artist, date, or city

View available seats

Browse available seats for an event, optionally filtered by type

Hold seats (temporary lock)

Temporarily hold selected seats for a configurable duration (10 min)

Confirm booking with payment

Process payment and confirm the booking within the hold window

Cancel booking and refund

Cancel a booking, release seats, and refund the payment

Expire stale holds

Background sweep to expire bookings whose hold timer has elapsed

Cancel event

Cancel an event and refund all associated bookings

Constraints

A seat can only be held by one booking at a time
Hold expires after 10 minutes if not confirmed (configurable)
Payment must succeed before booking is confirmed
Cancelled/expired holds must release seats back to AVAILABLE
Event cancellation must refund all confirmed bookings

Assumptions

In-memory storage (no database)
Single-threaded (concurrency is a follow-up)
Payment processing always succeeds (simulated)
No partial bookings — all requested seats must be available
One booking per customer per event (simplification)

In Scope

Venue with sections and typed seats
Event scheduling with per-type pricing
Seat hold mechanism with timeout
Booking lifecycle (PENDING → CONFIRMED / CANCELLED / EXPIRED)
Payment processing and refund
Event search and seat availability
Event cancellation with bulk refund

Out of Scope

Real payment gateway integration
Dynamic / surge pricing
Wait-list / queue when sold out
Resale / ticket transfer marketplace
QR code / digital ticket generation
Multi-event passes / season tickets

Approach Guide(Click to expand each section)

Before diving into code, clarify the use cases and edge cases. Understanding the problem deeply leads to better class design.

List Core Use Cases

Identify the primary actions users will perform. For a parking lot: park vehicle, exit vehicle, check availability. Each becomes a method.

Identify Actors

Who interacts with the system? Customers, admins, automated systems? Each actor type may need different interfaces.

Clarify Constraints

What are the limits? Max vehicles, supported vehicle types, payment methods. Constraints drive your data structures.

Ask About Edge Cases

What happens on overflow? Concurrent access? Payment failures? Thinking about edge cases reveals hidden complexity.

Follow-up Questions(Questions an interviewer might ask)

💡 Draw UML class diagrams, sequence diagrams, or any design visualizations. Submit from the Code tab.

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Loading LLD design...

00:00:00

Design a Concert Ticket Booking System

Intermediate

Core Use Cases

Create venues with seat maps

Schedule events

Create events at a venue with per-type pricing and sales status

Search events

Search by name, artist, date, or city

View available seats

Browse available seats for an event, optionally filtered by type

Hold seats (temporary lock)

Temporarily hold selected seats for a configurable duration (10 min)

Confirm booking with payment

Process payment and confirm the booking within the hold window

Cancel booking and refund

Cancel a booking, release seats, and refund the payment

Expire stale holds

Background sweep to expire bookings whose hold timer has elapsed

Cancel event

Cancel an event and refund all associated bookings

Constraints

A seat can only be held by one booking at a time
Hold expires after 10 minutes if not confirmed (configurable)
Payment must succeed before booking is confirmed
Cancelled/expired holds must release seats back to AVAILABLE
Event cancellation must refund all confirmed bookings

Assumptions

In-memory storage (no database)
Single-threaded (concurrency is a follow-up)
Payment processing always succeeds (simulated)
No partial bookings — all requested seats must be available
One booking per customer per event (simplification)

In Scope

Venue with sections and typed seats
Event scheduling with per-type pricing
Seat hold mechanism with timeout
Booking lifecycle (PENDING → CONFIRMED / CANCELLED / EXPIRED)
Payment processing and refund
Event search and seat availability
Event cancellation with bulk refund

Out of Scope

Real payment gateway integration
Dynamic / surge pricing
Wait-list / queue when sold out
Resale / ticket transfer marketplace
QR code / digital ticket generation
Multi-event passes / season tickets

Approach Guide(Click to expand each section)

Before diving into code, clarify the use cases and edge cases. Understanding the problem deeply leads to better class design.

List Core Use Cases

Identify the primary actions users will perform. For a parking lot: park vehicle, exit vehicle, check availability. Each becomes a method.

Identify Actors

Who interacts with the system? Customers, admins, automated systems? Each actor type may need different interfaces.

Clarify Constraints

What are the limits? Max vehicles, supported vehicle types, payment methods. Constraints drive your data structures.

Ask About Edge Cases

What happens on overflow? Concurrent access? Payment failures? Thinking about edge cases reveals hidden complexity.

Follow-up Questions(Questions an interviewer might ask)

💡 Draw UML class diagrams, sequence diagrams, or any design visualizations. Submit from the Code tab.

Loading canvas...

Design a Concert Ticket Booking System

Core Use Cases

Constraints

Assumptions

In Scope

Out of Scope

Approach Guide(Click to expand each section)

Follow-up Questions(Questions an interviewer might ask)

Explore the full editorial.

Sign in to view submissions

Design a Concert Ticket Booking System

Core Use Cases

Constraints

Assumptions

In Scope

Out of Scope

Approach Guide(Click to expand each section)

Follow-up Questions(Questions an interviewer might ask)

Explore the full editorial.

Sign in to view submissions

Design a Concert Ticket Booking System

Core Use Cases

Constraints

Assumptions

In Scope

Out of Scope

Approach Guide(Click to expand each section)

Gather Requirements~3 min

Identify Classes & Entities~4 min

Define Relationships~3 min

Apply Design Patterns~4 min

Apply SOLID Principles~3 min

Code Organization~2 min

Follow-up Questions(Questions an interviewer might ask)

1How would you handle thousands of concurrent users trying to book the same seats?

2How would you implement dynamic / surge pricing based on demand?

3How would you add a wait-list when an event is sold out?

4How would you support ticket transfers or a resale marketplace?

5How would you generate and validate digital tickets (QR codes)?

Key Topics

Asked At

Explore the full editorial.

Sign in to view submissions

Design a Concert Ticket Booking System

Core Use Cases

Constraints

Assumptions

In Scope

Out of Scope

Approach Guide(Click to expand each section)

Gather Requirements~3 min

Identify Classes & Entities~4 min

Define Relationships~3 min

Apply Design Patterns~4 min

Apply SOLID Principles~3 min

Code Organization~2 min

Follow-up Questions(Questions an interviewer might ask)

1How would you handle thousands of concurrent users trying to book the same seats?

2How would you implement dynamic / surge pricing based on demand?

3How would you add a wait-list when an event is sold out?

4How would you support ticket transfers or a resale marketplace?

5How would you generate and validate digital tickets (QR codes)?

Key Topics

Asked At

Explore the full editorial.

Sign in to view submissions