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Monolithic

Monolithic architecture is a traditional software architecture pattern where all components of an application are tightly coupled and run as a single service or executable. It's often used in small to medium-sized applications or in the early stages of development due to its simplicity.

Structure of a Monolithic Architecture​

A monolithic application typically has the following layers:

  1. Presentation Layer (UI)
  2. Business Logic Layer
  3. Data Access Layer
  4. Database

All of these layers are part of a single codebase and compiled/deployed together.

Characteristics of Monolithic Architecture​

FeatureDescription
Single CodebaseAll functionality is in one project/application.
Tightly CoupledComponents are dependent on each other.
Single DeploymentWhole application is built and deployed together.
Shared MemoryNo network calls between components; function calls are used.
Simple to Develop InitiallyEasy to set up and run during the early phase.

Advantages​

  • Simplicity – Easy to understand, develop, and deploy initially.
  • Performance – Inter-component calls are in-memory, hence faster.
  • Development Tools – Mature support in frameworks like Django, Spring Boot, Laravel, etc.
  • Ease of Testing – Can perform end-to-end testing easily in one place.

Disadvantages​

  • Scalability Limitations – You can’t scale individual components independently.
  • Tight Coupling – A change in one part may require redeploying the entire system.
  • Limited Agility – Difficult for multiple teams to work independently.
  • Deployment Risk – One bug can crash the whole app. Harder Maintenance – As the app grows, complexity becomes hard to manage.

When to Use Monolithic Architecture​

  • Small teams or projects with limited scope.
  • MVPs (Minimum Viable Products).
  • Applications that don't require high scalability or complex integrations.
  • Projects where time-to-market is more important than flexibility.

Transition Path​

Many startups begin with a monolithic architecture and later migrate to a microservices or modular architecture as the application scales and requires more flexibility.

Example of Monolithic Architecture​

Let’s consider an e-commerce platform with the following features:

  • User Authentication
  • Product Catalog
  • Shopping Cart
  • Order Management
  • Payment Processing
MonolithicApp/
│
├── controllers/
│   ├── AuthController.js
│   ├── ProductController.js
│   ├── CartController.js
│   └── OrderController.js
│
├── services/
│   ├── AuthService.js
│   ├── ProductService.js
│   ├── CartService.js
│   └── OrderService.js
│
├── models/
│   ├── User.js
│   ├── Product.js
│   └── Order.js
│
└── app.js

All these features are in one project and deployed together.