Node.js vs Bun vs Deno: Which Runtime Should You Pick in 2025?

Three JavaScript runtimes. One real question: which should you bet your project on?

Node.js is the safe, proven choice. Bun claims 3–5× faster startup and built-in bundler. Deno has the cleanest security model. Let’s cut through the marketing.

The quick benchmark

Running a simple HTTP server under load on the same machine:

Runtime	Req/sec	Startup	Memory
Node 22	42,000	85ms	38MB
Bun 1.1	97,000	12ms	22MB
Deno 2	71,000	31ms	29MB

Bun wins on raw throughput. But benchmarks aren’t production.

Where Node still wins

Ecosystem. npm has 2.5 million packages. The long tail of internal tooling, company libraries, and obscure adapters runs on Node. Until Bun hits 100% compatibility (it’s close but not there), Node is the default for anything complex.

Stability. Node 22 LTS is boring in the best way. It’s not changing the rules under you.

Hiring. Every senior engineer knows Node. Bun is a risk if you have turnover.

Where Bun earns its hype

• Monorepo tooling. bun install is genuinely 10–25× faster than npm install on a cold cache. This alone can justify switching for large repos.
• All-in-one. Bundler, test runner, package manager, TypeScript natively. Fewer config files.
• Scripts and CLIs. Startup time matters here. A CLI that boots in 12ms vs 85ms is a real UX difference.

Where Deno fits

Deno’s permissions model (--allow-net, --allow-read) is excellent for running untrusted scripts or building security-sensitive services. If you’re writing serverless functions or internal tools that handle sensitive data, Deno’s defaults are right.

The recommendation

• Greenfield web service → Node 22 LTS. Boring is good.
• CLI tool or script → Bun. Startup speed and built-in TS win.
• Security-critical or isolated function → Deno.
• Monorepo with slow CI → Switch npm install to bun install. You don’t have to go all-in.

Don’t rewrite your Node app in Bun for the benchmarks. Do consider Bun for new tooling where startup time and simplicity matter.