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Devii · Backend · 2026-06-18 · 8 min read

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Deno 2: Explicit Permissions, npm Compatibility, And JSR Packages

How Deno's flag-based sandbox differs from Node defaults, and what Deno 2 changed for ecosystem access.

**Deno** is a secure-by-default JavaScript and TypeScript runtime using V8 and Rust. **Deno 2** (released late 2024) improved **Node.js and npm compatibility** while keeping explicit **permission flags** for file, network, and environment access.

Scripts run without filesystem or network access unless you pass `--allow-read`, `--allow-net`, or scoped variants. This model suits CI scripts, edge templates, and teaching environments where implicit access is undesirable.

Package registry architecture
Package registry architecture

**JSR** (`jsr.io`) is Deno's modern package registry for TypeScript-first modules with native publishing tooling. Deno can also consume npm packages with lockfile support documented on `docs.deno.com`.

Deno Deploy provides hosted Deno functions at the edge. Evaluate Deno where permission clarity matters; evaluate Node where native module ecosystems are mandatory.