Deno vs Bun: Modern JavaScript Runtime Comparison (2026)

import ComparisonTable from ’../../components/ComparisonTable.astro’;

Both Deno and Bun are modern alternatives to Node.js with native TypeScript support. They represent different philosophies on how to improve the Node.js ecosystem.

Quick Verdict

Choose Deno if: Security is paramount (permissioned access to filesystem/network), you’re building for Deno Deploy edge platform, or you want the strictest standards-based runtime.

Choose Bun if: You want maximum speed, easiest Node.js migration, and best npm package compatibility.

Philosophy Comparison

Deno (Ryan Dahl, Node.js creator): “Fix Node.js by rewriting it correctly — secure by default, web standards first, no node_modules.”

Bun (Jarred Sumner): “Make JavaScript faster and simpler — drop-in Node.js replacement with 10x better performance.”

Different goals, different tradeoffs.

Feature Comparison

Deno’s Security Model

Deno’s permissions system is its most distinctive feature:

// deno.json - explicit permissions
{
  "permissions": {
    "read": ["./data", "./config"],
    "write": ["./output"],
    "net": ["api.example.com", "fonts.googleapis.com"],
    "env": ["API_KEY", "DATABASE_URL"]
  }
}

// Or at command line:
deno run --allow-read=./data --allow-net=api.example.com app.ts

// Runtime permission request:
const status = await Deno.permissions.request({ name: "read", path: "./data" });
if (status.state === "granted") {
  const content = await Deno.readTextFile("./data/config.json");
}

This means a compromised Deno application can’t read your SSH keys or call arbitrary external APIs — it can only access what you explicitly permitted.

For security-sensitive applications (processing untrusted input, sandboxed environments), Deno’s model is genuinely valuable.

Bun’s Speed

// Bun HTTP server — benchmark winner
const server = Bun.serve({
  port: 8080,
  fetch(req) {
    return new Response("Hello, World!", {
      headers: { "Content-Type": "text/plain" },
    });
  },
});

// Bun: ~127K req/s
// Deno: ~80K req/s  
// Node.js (Fastify): ~48K req/s
// Node.js (Express): ~21K req/s

Bun’s JavaScriptCore engine (same as Safari) + Zig systems code achieves faster throughput. For CPU-bound workloads, Bun is consistently faster than Deno.

TypeScript and Module System

Both handle TypeScript natively — no transpilation step:

// Deno uses URL imports and JSR (JavaScript Registry)
import { serve } from "jsr:@std/http";
import { z } from "npm:zod";  // npm packages via npm: prefix

// Bun uses npm imports directly
import { z } from "zod";  // Works like Node.js
import type { User } from "./types.ts";

Deno’s JSR (JavaScript Registry):

JSR is Deno’s modern package registry with TypeScript-first packages:

import { join } from "jsr:@std/path@^1.0";
import { assertEquals } from "jsr:@std/assert";

JSR publishes TypeScript source directly — no .d.ts files needed. Packages work in Deno, Bun, and Node.js.

Node.js Migration

Bun migration is often trivial:

# Replace npm/yarn with bun
bun install            # Reads package.json, creates bun.lockb
bun run start          # Runs start script
bun run dev            # Hot reload built-in

# Most Express/Fastify apps work without code changes

Deno migration requires more work:

// Node.js:
const fs = require('fs').promises;
const path = require('path');

// Deno (can use npm: prefix or std library):
import * as fs from "npm:fs";       // npm compat approach
// OR
import { join } from "jsr:@std/path";  // Deno-native approach
const content = await Deno.readTextFile("./file.txt");

Deno’s different module system and permissions require more migration effort for existing Node.js codebases.

Deployment and Hosting

Deno Deploy:

Deno’s own edge platform is excellent:

Deploy TypeScript code globally in seconds
No build step
V8 isolates at the edge
KV storage, queues, and cron built-in
GitHub integration for CI/CD

// Deno Deploy — runs at edge globally
Deno.serve(async (req) => {
  const url = new URL(req.url);
  
  if (url.pathname === "/api/data") {
    const kv = await Deno.openKv();
    const data = await kv.get(["key"]);
    return Response.json(data.value);
  }
  
  return new Response("Not found", { status: 404 });
});

Bun deployment:

Bun runs on any server (VPS, containers). Edge deployment options are limited compared to Deno Deploy.

When Deno Wins

Security-sensitive applications: Permissions model limits blast radius of vulnerabilities
Deno Deploy: Best-in-class edge deployment for Deno applications
Web standards compliance: Deno follows web platform APIs most closely
JSR packages: Growing ecosystem of TypeScript-first packages

When Bun Wins

Raw performance: Consistently faster throughput
Node.js migration: Closest to drop-in replacement
npm ecosystem: Smoother compatibility with existing packages
Developer tooling: Fastest installs and test runner

Bottom Line

Bun for most new applications — better npm compatibility, faster performance, and easier Node.js migration make it more practical in 2026. Deno for security-sensitive workloads, applications benefiting from its permissions model, or deployment on Deno Deploy’s edge platform. Both are significantly better than Node.js for new projects in terms of developer experience — the choice between them is about security model vs. performance/compatibility tradeoffs.