Bun vs Deno vs Node.js in 2026: Benchmarks, Code, and Real Numbers

Three runtimes. Three engines. One question: which one should you actually use?

I ran benchmarks, tested compatibility, and migrated real projects. Here's what I found.

The Engine Difference

Node.js  → V8 (Chrome)        → C++ + libuv
Deno     → V8 (Chrome)        → Rust
Bun      → JavaScriptCore (Safari) → Zig + io_uring

V8 optimizes for long-running processes. JavaScriptCore optimizes for fast startup. This single difference explains most benchmark results.

HTTP Throughput (Express, same code)

Bun:     52,000 req/sec
Deno:    29,000 req/sec
Node.js: 14,000 req/sec

Using native APIs instead of Express:

// Bun
Bun.serve({
  port: 3000,
  fetch: () => new Response("Hello")
});

// Deno
Deno.serve({ port: 3000 }, () => new Response("Hello"));

// Node.js
require('http').createServer((req, res) => 
  res.end("Hello")
).listen(3000);

Bun native: 68,000 req/sec. The gap widens.

Package Installation

Real monorepo, 1,847 dependencies:

npm install:  28 minutes
pnpm install: 4 minutes
bun install:  47 seconds

Bun uses binary lockfile (bun.lockb) and global cache. No node_modules bloat on repeated installs.

TypeScript Execution

# Bun - just works
bun index.ts

# Deno - just works
deno run index.ts

# Node.js - needs flag (experimental, strips types only)
node --experimental-strip-types index.ts

Node.js type stripping doesn't transpile. No enums, no decorators, no namespace. For production Node.js, you still need tsc or esbuild.

Cold Start (AWS Lambda)

Node.js: 245ms average
Bun:     156ms average

35% faster cold starts = 35% lower Lambda bills on compute-heavy workloads.

Memory Usage

Bun 1.3 reduced memory 10-30% in Next.js and Elysia apps. Real numbers from production:

Next.js on Node.js: 512MB baseline
Next.js on Bun:     380MB baseline

Security Model

// Deno - explicit permissions required
deno run --allow-net --allow-read server.ts

// Bun/Node.js - full system access by default
bun server.ts
node server.ts

Deno sandboxes everything. Compromised npm package can't exfiltrate data without --allow-net. Node.js and Bun trust all code completely.

Node.js API Compatibility

Bun 1.2+ implements most Node.js APIs:

// Works in Bun
import fs from 'fs';
import path from 'path';
import { Buffer } from 'buffer';
import express from 'express';

Edge cases break: native addons, obscure Node internals, some streams behavior.

Deno 2 added npm: specifiers:

// Deno
import express from "npm:express";

Works, but CommonJS packages sometimes need adjustments.

Built-in Tools

              | Node.js | Deno | Bun
--------------|---------|------|-----
Package mgr   |   ✗     |  ✓   |  ✓
Bundler       |   ✗     |  ✓   |  ✓
Test runner   |   ✓     |  ✓   |  ✓
TypeScript    |   ~     |  ✓   |  ✓
Formatter     |   ✗     |  ✓   |  ✗
Linter        |   ✗     |  ✓   |  ✗

Bun test runner is 20x faster than Jest. Same syntax:

import { test, expect } from "bun:test";

test("math works", () => {
  expect(2 + 2).toBe(4);
});

When to Use What

Node.js: Legacy codebases, maximum npm compatibility, enterprise LTS requirements

Deno: Security-critical apps, greenfield TypeScript projects, edge deployment via Deno Deploy

Bun: Performance-critical APIs, fast local development, serverless where cold start matters

Migration Path

Lowest risk approach:

# Step 1: Use Bun for dev, deploy to Node.js
bun install        # instead of npm install
bun test          # instead of jest
bun run dev       # same scripts work

# Step 2: Test production compatibility
bun build ./src/index.ts --outdir ./dist

# Step 3: Switch runtime when confident

Most Express/Fastify apps run on Bun without code changes.

TL;DR

Bun is fastest. Deno is most secure. Node.js is most compatible.

All three are production-ready in 2026.

Pick based on your constraints, not Twitter hype.

# Try it yourself
curl -fsSL https://bun.sh/install | bash
bun --version