JavaScript on the backend, sharing code and context with the frontend
Node.js is a JavaScript runtime that lets the same language used in the browser run on the server powering everything from lightweight APIs to full backend services, with an ecosystem (npm) that's the largest package registry in the industry.
For teams building with JavaScript or TypeScript across the stack, Node.js removes the context-switching cost of a separate backend language, and its event-driven, non-blocking model handles high-concurrency workloads many simultaneous API requests or WebSocket connections efficiently.
We use Node.js for backend services where JavaScript's ecosystem and concurrency model fit the problem API layers, real-time features, and services that sit alongside a React or Next.js frontend sharing types and validation logic.