Bun vs Node.js: Is It Time to Switch in 2026?

Bun has been making noise since it launched, promising faster startup times, built-in TypeScript support, and a batteries-included runtime. But is it actually ready to replace Node.js for real projects in 2026? I ran the benchmarks, migrated a side project, and here is what I found.

What Is Bun?

Bun is a JavaScript runtime built from scratch using Zig and JavaScriptCore (the same engine that powers Safari). It ships as a single binary that replaces Node.js, npm, and even a bundler like esbuild — all in one tool.

Key selling points:

Fast startup — JavaScriptCore boots significantly faster than V8 in cold-start scenarios
Built-in TypeScript — no need for ts-node or a separate build step
Built-in bundler and test runner — bun build, bun test out of the box
npm compatible — reads package.json, installs from the npm registry, compatible with most packages

The Benchmark Reality

Everyone quotes Bun’s “3x faster than Node.js” headline. Here is what that actually means in practice.

HTTP throughput

# Bun HTTP server
bun run server.ts
# ~120,000 requests/sec

# Node.js HTTP server
node server.js
# ~45,000 requests/sec

Bun wins significantly on raw HTTP throughput. This matters if you are building a high-traffic API without a framework layer.

Startup time

time bun run index.ts
# real 0m0.043s

time node index.js
# real 0m0.178s

Bun starts about 4x faster. This is relevant for CLI tools, scripts, and serverless cold starts.

Real-world Express app

Once you add a framework like Express, the gap narrows considerably because the bottleneck moves to your application logic, database queries, and network I/O — not the runtime.

Ecosystem Compatibility in 2026

This was my biggest concern when I tried migrating a side project. Here is the honest state of things:

Works great:

Express, Hono, Elysia, Fastify
Prisma (after v5.4)
Most utility libraries (lodash, date-fns, zod, etc.)
React, Vue, Svelte (for SSR)

Still rough:

Some native Node.js addons (.node bindings) do not work
A handful of packages that rely on internal Node.js APIs
Some edge cases with node:crypto and node:stream

The compatibility surface is around 95% for typical web applications. The remaining 5% can be a dealbreaker depending on your stack.

When to Actually Switch

After testing this properly, here is my practical take:

Switch to Bun if:

You are building a new project from scratch — no migration cost
You are writing CLI tools or scripts — startup speed matters, and native TypeScript is a huge quality-of-life improvement
You are building a high-performance API without heavy legacy dependencies
You want to simplify your toolchain (no more npm + tsc + jest + esbuild separately)

Stick with Node.js if:

You have a large existing codebase — the migration risk is not worth it unless you have a specific pain point
You rely on native addons or obscure internal Node.js APIs
Your team needs battle-tested production stability with years of known behavior

Migrating a Project: What It Actually Looks Like

I migrated a small Express API (about 3,000 lines) to Bun. The process:

# Install Bun
curl -fsSL https://bun.sh/install | bash

# Replace package manager
bun install  # reads existing package.json

# Run your app
bun run index.ts  # TypeScript, no config needed

That was mostly it. I hit two issues:

One package used __dirname in a way Bun handled slightly differently — fixed with a one-liner shim.
My Jest tests needed migration to bun test — took about 30 minutes to swap the imports.

Total migration time: about 2 hours for a medium-sized project.

The Bun-Native Stack

If you are starting fresh, the most ergonomic stack in 2026 looks like:

bun create hono my-app

Hono is a lightweight, Bun-first web framework that pairs perfectly with Bun’s performance profile. Add Prisma for the database layer and you have a modern backend that is genuinely fast to develop and fast to run.

Conclusion

Bun is no longer a beta experiment. It is stable, fast, and compatible enough for most projects in 2026. If you are starting something new, there is little reason not to use it. If you are maintaining existing Node.js code, a migration is worth evaluating but not urgent.

The honest answer to “should I switch?” is: start your next project with Bun and decide for yourself. The startup time alone makes it worth it for scripts and tooling.