What is the server-side JavaScript runtime built on V8?

The server-side JavaScript runtime built on Google’s V8 engine is Node.js.

Node.js is a cross-platform, open-source JavaScript runtime environment that executes JavaScript outside a web browser. It combines V8, the engine originally developed for Google Chrome, with APIs for networking, files, processes, and other operating-system tasks. This lets developers use JavaScript for web servers, command-line tools, automation, and backend services.

Node.js was created by Ryan Dahl and publicly demonstrated at the first European JSConf in 2009. Its design emphasizes event-driven programming and non-blocking input/output. An event loop coordinates callbacks and asynchronous operations, while the libuv library supplies much of the cross-platform networking and file-system infrastructure. This model is well suited to many concurrent I/O tasks, though CPU-heavy work can still block the main event loop.

npm, introduced for the Node.js ecosystem in 2010, is a package manager and registry rather than the runtime itself. Deno is another V8-based runtime, while Bun uses JavaScriptCore. Those are genuine alternatives, but Node.js is the canonical answer to this wording because it is the runtime historically and commonly identified with server-side JavaScript on V8.