NestJS

NestJS is a progressive Node.js framework for building scalable server-side applications. It uses TypeScript by default and supports pure JavaScript. It emphasizes modular architecture and uses decorators, modules, controllers, and providers. It draws architectural inspiration from Angular, applying dependency injection and an emphasis on testability and maintainability.

NestJS runs on Node.js and uses Express by default as the HTTP platform, but it can operate with alternative underlying adapters such as Fastify for improved performance. It provides a layered architecture that abstracts HTTP handling while allowing low-level access when needed.

Core concepts include modules (grouped components), controllers (receive requests), providers (services and other injectable values), and a dependency-injection container. It supports middleware, guards, interceptors, pipes, and filters to customize request handling, validation, and error management.

The framework supports multiple transport layers for microservices and a range of application patterns. It offers built-in support for REST APIs, GraphQL, WebSockets, and microservice messaging using TCP, Redis, NATS, MQTT, among others. The CLI aids in project scaffolding and resource generation.

Since its release, NestJS has grown a large ecosystem and active community. It integrates with databases and ORMs such as TypeORM, Prisma, Mongoose, and Sequelize; supports testing with Jest; and offers official and community modules for authentication, authorization, and utilities. It is MIT-licensed and widely adopted in enterprise and startup projects.