Summary of 12 important architecture patterns used in real-world large systems.

1.Monolithic Architecture

All components exist in one single application. Example structure:

Application
 ├── Authentication
 ├── Orders
 ├── Payments
 ├── Database

Used by

• Many startups initially
• Early versions of Amazon and Facebook

Pros

✔ Simple to develop
✔ Easy to deploy

Cons

❌ Hard to scale large systems

2. Microservices Architecture

Application split into small independent services.

Example:

API Gateway
   ↓
User Service
Order Service
Payment Service
Notification Service

Used by

• Netflix
• Uber
• Amazon
• Spotify

Benefits

✔ Independent scaling
✔ Independent deployment

3. Event-Driven Architecture

Systems communicate using events instead of direct calls.

Example:

Order Placed
     ↓
Kafka
     ↓
Payment Service
Inventory Service
Notification Service

Used by

• Uber
• LinkedIn
• Netflix

4. Serverless Architecture

Backend functions run without managing servers.

Example:

User Request
     ↓
API Gateway
     ↓
Lambda Function
     ↓
Database

Used by

• Airbnb
• Netflix
• Many startups

5. Layered Architecture

Application split into layers.

Example:

Presentation Layer
Business Layer
Data Access Layer
Database

Django/FastAPI apps already follow this pattern.

6. Clean Architecture

Core business logic is independent of frameworks.

Structure:

Entities
Use Cases
Interface Adapters
Frameworks

Why it’s powerful

You can switch:

• Django → FastAPI
• PostgreSQL → MongoDB

without affecting business logic.

7. Hexagonal Architecture (Ports & Adapters)

Separates business logic from external systems.

Example:

Domain Logic
     ↓
Ports
     ↓
Adapters
  ├ Database
  ├ REST API
  ├ Message Queue

Very useful for large backend systems.

8. CQRS Architecture

Separates read operations and write operations.

Example:

Command Service → Write DB
Query Service → Read DB

Used by

• Large financial systems
• High scale SaaS systems

9. Event Sourcing

Instead of storing current state, store all events.

Example:

Account Created
Money Deposited
Money Withdrawn

Current state is calculated from events.

Used by

• Banking systems
• Financial ledgers

10. API Gateway Architecture

A single entry point for all services.

Example:

Client
   ↓
API Gateway
   ↓
User Service
Order Service
Payment Service

Used by

• Netflix
• Amazon
• Uber

11. Space-Based Architecture

Designed for very high scalability.

Uses in-memory data grids instead of central database.

Used by

• Financial trading platforms
• Real-time analytics systems

12. Peer-to-Peer Architecture

Every node acts as both client and server.

Used by

• Blockchain
• Torrent systems
• Distributed networks