Deno is an open source JavaScript and TypeScript runtime created by Ryan Dahl, the author of Node.js, and introduced in 2018 as a fix for the design choices he regretted in Node.
It is written in Rust and built on the V8 engine. Three choices set it apart. Security by default: a script can only access the network, files or environment variables if explicitly allowed. TypeScript works with no configuration. And it follows browser standards (fetch, ES modules, Web APIs).
Deno also ships its own built-in tools: formatter, linter, test runner. Version 2, released in 2024, significantly improved compatibility with Node.js and npm packages, which makes gradual adoption easier.
The company behind Deno also offers Deno Deploy, a platform for running code at the edge. It is found in scripts, internal tools and lightweight back-end services.
Why it matters when hiring
As with Bun, a good TypeScript or Node.js developer learns Deno quickly: there is no point making it a deal-breaker. The interesting signal: a candidate who can explain the permission model and why they chose Deno over Node.js on a given project. It shows perspective on their tools more than a rare skill.