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Introduction to Deno

Deno (/ˈdiːnoʊ/, pronounced dee-no) is a JavaScript, TypeScript, and WebAssembly runtime with secure defaults and a great developer experience. It’s built on V8, Rust, and Tokio.

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Why Deno?

Deno was created to address shortcomings in Node.js by providing a modern runtime with better security, built-in TypeScript support, and improved developer experience.

Secure by Default

No file, network, or environment access unless explicitly enabled. Run untrusted code with confidence.

TypeScript Built-in

First-class TypeScript support out of the box. No configuration needed.

Modern Standards

Built on web standards with support for ES modules, fetch API, and Web APIs.

Great Tooling

Built-in formatter, linter, test runner, and bundler. Everything you need in one tool.

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Key Features

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Security First

Deno is secure by default. Scripts cannot access files, the network, or the environment without explicit permission. This makes it safe to run untrusted code. 
# This will fail without --allow-read permission
deno run script.ts

# Grant specific permissions
deno run --allow-read --allow-net script.ts

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TypeScript Native

TypeScript works out of the box - no configuration required: 
function greet(name: string): string {
  return `Hello, ${name}!`;
}

console.log(greet("World"));

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Web Standard APIs

Deno implements standard web APIs like fetch, Request, Response, and more: 
const response = await fetch("https://api.example.com/data");
const data = await response.json();
console.log(data);

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Built-in Tooling

Everything you need is built into the deno executable:
  • Formatter: deno fmt - Format your code
  • Linter: deno lint - Catch common errors
  • Test Runner: deno test - Run your tests
  • Bundler: deno bundle - Bundle your code
  • Documentation: deno doc - Generate documentation
  • REPL: deno - Interactive shell

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Quick Start

Installation

Get Deno installed on your system in seconds

Quickstart

Build and run your first Deno program

First Steps

Learn basic commands and explore Deno’s features

API Reference

Complete API documentation and examples

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Runtime Architecture

Deno is built on three core technologies:
  • V8: Google’s JavaScript engine, the same used in Chrome
  • Rust: Systems programming language providing speed and safety
  • Tokio: Asynchronous runtime for Rust, enabling efficient I/O
This combination provides excellent performance while maintaining security and developer experience.

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Additional Resources

Deno Standard Library

Officially supported common utilities for Deno programs

JSR Package Registry

The open-source package registry for modern JavaScript and TypeScript

Developer Blog

Product updates, tutorials, and more from the Deno team

Official Docs

Comprehensive guides and reference documentation

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Next Steps

Ready to get started? Follow our installation guide to install Deno, then try the quickstart tutorial to build your first application.

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