Deno

Permissions Model

Secure by default. Scripts need explicit --allow-read, --allow-write, --allow-net, --allow-env, or --allow-run flags. Permissions can be scoped to specific paths or domains.

Standard Library

Curated std library at jsr.io/@std/. Includes HTTP, filesystem, streams, testing, encoding, and crypto. Zero external dependencies.

URL Imports

Modules imported directly from URLs. No node_modules or package.json needed. Supports npm specifiers (npm:express) and JSR specifiers.

Deno.serve

Built-in HTTP server with simple Deno.serve(handler). Supports HTTP/1.1, HTTP/2, and TLS.

KV Store

Deno.openKv() provides SQLite-backed key-value storage. Supports atomic operations, transactions, secondary indexes, and queue listeners.

npm Compatibility

Use npm packages via npm: specifiers. Built-in Node.js compatibility layer works with most packages.

Deno compile

Bundle scripts into standalone executables. Includes runtime and dependencies in a single binary.

Testing

Deno.test() with code coverage, resource sanitization, and leak detection built in.