Deno vs Bun: Which JavaScript Runtime Wins in 2026?

The JavaScript runtime wars have never been more interesting. In 2026, Deno and Bun have each carved out real developer mindshare, and both have matured significantly since their initial releases. Node.js still dominates production workloads, but teams starting new projects increasingly ask: should we use Deno or Bun?

This guide gives you the technical depth to answer that question for your specific context.

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Quick Comparison: At a Glance

	Deno	Bun
Creator	Ryan Dahl (Node.js creator)	Jarred Sumner
First release	2020	2022
Language	Rust + V8	Zig + JavaScriptCore
Node.js compat	~95% (via node: prefix)	~98%
TypeScript	Native (no build step)	Native (no build step)
Package manager	Built-in (deno add)	Built-in (bun add)
Test runner	Built-in (deno test)	Built-in (bun test)
Bundler	Built-in (deno bundle)	Built-in (bun build)
HTTP performance	~150k req/sec	~200k req/sec
Install speed	Fast	~25× faster than npm
Security	Permissions-based sandbox	No sandbox
npm registry	Full access (npm: prefix)	Full access
License	MIT	MIT

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What is Deno?

Deno was created by Ryan Dahl — the original creator of Node.js — as his “do-over” addressing Node’s design mistakes. Dahl famously listed ten things he regretted about Node.js in his 2018 JSConf talk, and Deno is the direct answer to those criticisms.

Deno 2.0, released in 2024, was a watershed moment. It abandoned the “no npm” ideology and added full npm compatibility, making it a genuine production option rather than an experiment.

Core design principles:

• Security by default — scripts require explicit permissions (--allow-read, --allow-net, etc.)
• TypeScript as a first-class citizen — no ts-node or build step required
• Web standards alignment — fetch, ReadableStream, URL, WebCrypto all built-in
• Single executable — one binary, no node_modules, no global installs
• URL imports — direct import from URLs (plus JSR, the JavaScript Registry)

What is Bun?

Bun launched in 2022 with a simple premise: be the fastest JavaScript runtime possible. Built on JavaScriptCore (the engine that powers Safari) and written in Zig, Bun focused ruthlessly on performance and drop-in Node.js compatibility.

Bun’s architecture choice is notable: JavaScriptCore (JSC) vs. V8 is a real trade-off. JSC is faster at startup and has better performance for short-lived scripts; V8 is more mature and has years of JIT tuning for long-running server workloads.

Core design principles:

• Speed first — startup time, install speed, test runner speed, HTTP throughput
• Node.js drop-in — run Node.js apps with zero or minimal changes
• All-in-one — runtime + package manager + bundler + test runner in one binary
• SQLite built-in — bun:sqlite is a first-class, zero-dependency SQLite driver

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Performance Benchmarks 2026

HTTP Server Throughput

// Simple HTTP server — same code, different runtimes
const server = Deno.serve({ port: 3000 }, () => new Response("Hello"));

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

Runtime	Req/sec (simple)	Latency p50	Latency p99
Bun 1.2	~220,000	0.8ms	3.2ms
Deno 2.1	~165,000	1.1ms	4.5ms
Node.js 22	~85,000	2.4ms	8.1ms

Benchmarks: wrk 4 threads, 100 connections, 10s duration, Apple M3 Pro. Exact numbers vary by hardware.

Package Install Speed

# Installing a fresh Next.js project
bun install           # ~2.1s
npm install           # ~52s
pnpm install          # ~28s
yarn install          # ~38s
deno add next         # ~4.8s (with node_modules)

Bun’s install speed is genuinely impressive — it uses a binary lockfile format and parallel downloads with system-level file operations.

Test Runner Performance

# Running 1000 unit tests
bun test              # ~0.8s
deno test             # ~3.2s
vitest                # ~8.5s
jest                  # ~22s

Startup Time

# Time to first output: console.log("hi")
bun hello.ts          # 4ms
deno run hello.ts     # 18ms
node hello.js         # 28ms
ts-node hello.ts      # ~2500ms

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Node.js Compatibility

Both runtimes aim for Node.js compatibility, but they approach it differently.

Bun’s Approach

Bun implements Node.js APIs directly. Most Node.js projects run with bun run and zero changes:

# Just replace 'node' with 'bun'
bun run index.js
bun run server.js

# Or run npm scripts
bun run dev
bun run build

Common Node.js APIs supported: fs, path, os, crypto, http, https, net, tls, child_process, cluster, events, stream, buffer, util, url, querystring, dns, readline, zlib.

Known gaps in 2026: some native addons (.node files) don’t work, some vm module edge cases, and a few worker_threads features have differences.

Deno’s Approach

Deno uses a node: prefix for Node compatibility:

// Deno with Node compat
import { readFileSync } from "node:fs";
import path from "node:path";
import { createServer } from "node:http";

Or add to deno.json:

{
  "nodeModulesDir": "auto"
}

Deno’s compat layer has improved dramatically. Express, Fastify, Hono, and most popular packages work. However, some low-level native modules and packages that rely on __dirname/__filename in specific ways may need adjustments.

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Security Model

This is where Deno and Bun diverge most philosophically.

Deno’s Permission System

# Explicit permissions required
deno run --allow-net server.ts          # network access
deno run --allow-read=./data script.ts  # read only from ./data
deno run --allow-write=/tmp script.ts   # write only to /tmp
deno run --allow-env=PORT script.ts     # only read PORT env var
deno run --allow-run=git script.ts      # only exec git

# Run with no permissions (sandboxed)
deno run script.ts  # fails if script tries to access fs/net

This model is excellent for running untrusted code, CI scripts, or serverless functions where you want to limit blast radius. It’s also useful for auditing what a script actually needs.

Bun’s Approach

Bun has no sandboxing. Scripts run with the same permissions as the user. This matches Node.js behavior and is simpler to reason about, but means you have no built-in protection against a dependency doing something unexpected.

Which is better? For user-written server applications: Bun’s model is simpler and you’ll never hit a “forgot to add —allow-net” error. For running third-party scripts or building a platform where untrusted code runs: Deno’s permissions are a genuine security feature.

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TypeScript Support

Both runtimes run TypeScript natively without a build step. The difference is in implementation details.

// Works in both Deno and Bun without transpilation
interface User {
  id: number;
  name: string;
  email: string;
}

async function fetchUser(id: number): Promise<User> {
  const res = await fetch(`/api/users/${id}`);
  return res.json() as Promise<User>;
}

Deno: Uses its own TypeScript compiler. Supports tsconfig.json as deno.json. Can use deno check for type verification without running the code.

Bun: Uses its own Zig-based TypeScript transpiler (not tsc). Extremely fast — transpiles TypeScript ~15× faster than tsc. However, it does not do type checking — it strips types and runs. Use tsc --noEmit separately if you need type safety at CI time.

# Deno type checks AND runs
deno run --check script.ts

# Bun transpiles without type-checking
bun run script.ts
bun run --bun tsc --noEmit  # separate type check

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Package Management

Bun

bun add express hono
bun add -d @types/node typescript
bun remove lodash
bun update

# Lockfile: bun.lockb (binary, fast)
# Uses node_modules/

Deno

# New: deno add (uses JSR or npm)
deno add @std/fs
deno add npm:express

# deno.json imports map
{
  "imports": {
    "hono": "npm:hono",
    "std/": "jsr:@std/"
  }
}

Deno’s ecosystem push toward JSR (JavaScript Registry) is interesting. JSR is designed for TypeScript-native packages with proper type exports and cross-runtime support. Packages like @std/path, @std/fs, and @hono/hono are published to JSR with better TypeScript support than npm equivalents.

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Built-in Tooling

Tool	Deno	Bun
Test runner	deno test	bun test
Bundler	deno bundle / deno compile	bun build
Formatter	deno fmt (opinionated)	—
Linter	deno lint	—
REPL	deno repl	bun repl
Scripts	deno task	bun run (package.json)
Benchmarks	deno bench	bun bench
Compile to binary	deno compile	bun build --compile

Deno’s built-in formatter and linter are notable. deno fmt is opinionated (similar to Prettier) and deno lint includes rules for security and correctness. Teams that want zero config tooling appreciate this.

Compiling to Standalone Executables

Both runtimes can compile your TypeScript/JavaScript to a single executable:

# Deno
deno compile --allow-net --output myapp server.ts
# Produces: myapp (10-30MB binary)

# Bun
bun build --compile --outfile myapp server.ts
# Produces: myapp (5-15MB binary)

This is powerful for CLI tools, deployment artifacts, and edge cases where you don’t want to install a runtime.

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SQLite Support

Bun has a first-class, zero-dependency SQLite driver:

// Bun
import { Database } from "bun:sqlite";

const db = new Database("myapp.db");
db.run(`CREATE TABLE IF NOT EXISTS users (id INTEGER PRIMARY KEY, name TEXT)`);

const insert = db.prepare("INSERT INTO users (name) VALUES (?)");
insert.run("Alice");

const users = db.query("SELECT * FROM users").all();
console.log(users); // [{ id: 1, name: "Alice" }]

Deno has @std/sqlite but it’s a WASM-based implementation — functional, but slower than Bun’s native bindings. For SQLite-heavy workloads, Bun wins clearly.

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Web Standards Compliance

Deno leads here by design. It implements web APIs as closely as possible to browser standards:

// Deno — all these are built-in, matching browser APIs
const response = await fetch("https://api.example.com/data");
const text = await response.text();

const stream = new ReadableStream({
  start(controller) {
    controller.enqueue("hello");
    controller.close();
  }
});

const hash = await crypto.subtle.digest("SHA-256", new TextEncoder().encode("hello"));

Bun also supports most Web APIs but Deno’s compliance is more complete and deliberate. If you’re writing code that should run in browsers, Workers, and servers, Deno’s web-standard-first approach reduces cognitive overhead.

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Use Cases: When to Choose Which

Choose Bun When:

• Migrating a Node.js project — highest compatibility, minimal changes needed
• Performance is critical — both HTTP throughput and startup time
• You want the fastest package installs — 10-25× faster than npm matters in CI
• SQLite is part of your stack — built-in driver is excellent
• You use Elysia — the Bun-native web framework with exceptional performance
• CLI tools — fast startup + compile-to-binary is a great combo

Choose Deno When:

• Security matters — you want sandboxed script execution
• Running scripts from untrusted sources — CI pipelines, user-provided code
• TypeScript-first projects — especially with JSR packages
• Web platform code sharing — code that might also run in browsers/Workers
• Want all-in-one tooling — formatter, linter, test runner, task runner
• Edge deployment — Deno Deploy has excellent Deno integration

Stick with Node.js When:

• Native addons — compiled .node modules
• Mature ecosystem requirement — some enterprise tools only publish Node.js packages
• Large existing codebase — migration risk outweighs runtime benefits

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Ecosystem and Community

npm downloads (monthly, 2026 estimate):
Node.js: ~3B
Bun:     ~45M
Deno:    ~12M

Node.js still dominates by orders of magnitude. But both Deno and Bun have active communities:

• Deno: Strong standard library (@std/*), JSR growing, good documentation, Deno Deploy cloud platform
• Bun: Rapidly growing, active Discord (~50k members), Elysia framework ecosystem, strong community tooling

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Deployment Options

Platform	Bun	Deno
Docker	✅ Official image	✅ Official image
Fly.io	✅	✅
Render	✅	✅
Railway	✅	✅
Vercel	⚠️ Node.js mode	✅ Edge Functions native
Cloudflare Workers	❌	✅ via Deno Deploy
AWS Lambda	✅ (container)	✅ (container)

Deno has an edge in serverless/edge deployment through Deno Deploy. Bun works well anywhere you can run a container.

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The Verdict

Neither Bun nor Deno is objectively better — they optimize for different things.

Bun wins on raw performance, Node.js compatibility, and install speed. If you’re replacing Node.js and want the fastest possible runtime with the least friction, Bun is the choice.

Deno wins on security, web standards alignment, and built-in tooling breadth. If you want a principled, secure-by-default runtime with an excellent standard library, Deno is compelling.

In 2026, both are production-ready. The best choice depends on your team’s priorities: compatibility and speed (Bun) or security and standards (Deno).

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Quick Start

Bun

curl -fsSL https://bun.sh/install | bash
bun --version
bun init my-app
cd my-app
bun run index.ts

Deno

curl -fsSL https://deno.land/install.sh | sh
deno --version
deno init my-app
cd my-app
deno run main.ts

Both runtimes install in seconds and run your first script with no configuration. The best way to form an opinion is to try both on a project you know well and see which one feels right.