What Is Node.js and What Projects Is It Used For?

What is Node.js exactly, and why do so many companies use it to build their back-ends instead of more traditional alternatives? This server-side JavaScript technology deserves to be well understood before it's chosen for a project, since the fit matters more than the hype around it.

A server-side JavaScript runtime

Node.js lets you run JavaScript code outside the browser, on the server. Built on Google Chrome's V8 engine, it relies on a non-blocking, event-driven architecture that's particularly well suited to handling a large number of simultaneous connections without consuming excessive resources or requiring a dedicated thread for each one.

Types of projects suited to Node.js

• REST or GraphQL APIs that power web or mobile applications
• Applications that need real-time exchanges, such as instant messaging or push notifications
• Microservices-oriented architectures, where several small services communicate with each other
• Internal tools that need good responsiveness under significant request volume

Limitations worth knowing

Node.js is less suited to very compute-intensive workloads, such as heavy image processing or complex scientific calculations, where other environments may offer better performance. It's therefore worth choosing Node.js based on the actual nature of the expected workload rather than general popularity alone.

Why so many companies use it

Beyond its technical qualities, Node.js benefits from a very rich ecosystem of freely available libraries, which often speeds up development by building on proven building blocks rather than reinventing everything from scratch. Using JavaScript on both the front-end and the back-end also makes it easier to organize teams, since some developers can work across both layers of an application depending on project needs.

A technology suited to many contexts

From startups to large enterprises, Node.js is used in very diverse contexts: mobile app back-ends, streaming platforms, collaborative tools, and high-load internal services. To go further, read our complete guide to Node.js, the dedicated blog section, and the Node.js projects published on the platform.