Next.js VS Express.js VS NestJS

1. Common:

• Based on JavaScript/TypeScript: All three frameworks allow you to develop applications using either JavaScript or TypeScript.
• Based on Node.js: Each framework runs on top of Node.js. What they have in common is that you can develop backend applications using JavaScript/TypeScript on the server side.
• Supports REST API development: Express.js, NestJS, and Next.js (when leveraging server-side features) all make it easy to build REST APIs.
• Module system: Supports modular development methods such as TypeScript, and the module system allows you to structure and manage your code.

2. Characteristics and roles of each framework:

Next.js:

• Role: A front-end framework that supports React-based Server-Side Rendering (SSR) and Static Site Generation (SSG). It also supports backend features such as serverless functions.
• Main features:
• SSR and SSG: Render pages server-side or generate static pages at build time.
• Routing system: Provides a file-based routing system for easy page management.
• API Routing: You can define a simple backend API within the /api directory.
• Backend relevance: Basically, Next.js is a frontend framework, but you can develop full-stack applications by leveraging serverless environments or integrating with backend frameworks like Express.js.

Express.js:

• Role: Backend web application framework, helping you develop REST APIs or web applications in a simple and flexible way.
• Main features:
• Routing: Provides routing functions to handle various HTTP requests.
• Middleware: You can configure a server flexibly by connecting multiple middleware that handles requests and responses.
• Affinities with other frameworks: Express.js is a backend-focused framework that can be easily integrated with frontend frameworks (e.g. Next.js). In fact, you can even build more complex backends by replacing Next.js’ API routing functionality with Express.js.

NestJS:

• Role: A backend application framework that helps you write structured, modular code inspired by Angular. Ideal for developing large-scale enterprise applications.
• Main features:
• Modularization: NestJS maximizes code reusability through a module system and can manage various functions by separating them into separate modules.
• Decoupled Architecture: Use dependency injection to increase maintainability and testability of your code.
• Supports GraphQL, WebSocket, Microservices: Supports various communication methods in addition to REST API.
• Associativity with other frameworks: It can be closely integrated with Express.js and basically uses Express.js internally. NestJS can also use other HTTP servers like Fastify instead of Express.js. It can also be used with Next.js to create full-stack applications that use NestJS as the backend and Next.js as the frontend.

3. Relevance Summary:

• Next.js primarily handles the frontend (SSR and SSG) and can provide simple backend functionality via API routes. When you have more complex backend needs, you can use it by integrating with Express.js or NestJS.
• Express.js is a flexible backend framework, suitable for simple server development. NestJS is an enterprise-grade framework that uses Express.js internally, but provides greater structure and extensibility.
• NestJS is designed for advanced backend development and is more structured than Express.js in that it supports dependency injection, modularity, and a variety of communication methods. NestJS can be combined with Next.js as a frontend to develop complete full-stack applications.