NestJS structures Node.jsA JavaScript runtime built on V8 — event-driven I/O for servers, CLIs, and tooling. backends like Spring or Angular — modules, controllers, dependency injection, decorators. Used for RESTRepresentational State Transfer — a style for web APIs using HTTP methods and resource URLs. and GraphQL APIs, microservicesAn architecture splitting applications into small independent services — each deployed and scaled separately., and enterprise TypeScriptJavaScript with static types — compiles to JS and powers large front-end and Node codebases. servers. Example: a typed APIApplication programming interface — a defined way for programs to talk to each other or to a service. with auth guards, Swagger docs, and PostgreSQL via TypeORM — without Express spaghetti.

NestJS brought structure to NodeNode.js — JavaScript on the server via an event-driven runtime built on V8. backends when Express-only codebases became hard to maintain at scale.

Decorators, dependency injection, and modules made enterprise patterns normal in TypeScriptJavaScript with static types — compiles to JS and powers large front-end and Node codebases. APIs.