The State of JavaScript Runtimes in 2025: Node, Deno, and Bun

When Bun 1.0 shipped in September 2023 and Deno 2.0 landed in late 2024, a lot of people (myself included) wondered whether the JavaScript runtime market could support three serious competitors. Two years later, I think we have our answer: yes, but not in the way anyone expected.

Each runtime has settled into its own niche, and the competition has pushed all three to improve faster than any of them would have alone. That is a win for everyone writing JavaScript.

Node.js 22+

Node.js is the default. That has not changed. The npm ecosystem, the hiring pool, the documentation, the battle-tested production stories. If you pick Node for a project, nobody is going to question your judgment.

But Node has also gotten significantly better at absorbing the good ideas from its competitors. The built-in test runner (node --test) is now stable and genuinely useful. The --watch flag for automatic restarts works well enough that many teams have dropped nodemon. Native .env file support means one less dependency. The experimental permission model gives you some of the sandboxing that Deno pioneered.

// Node.js 22 built-in test runner
import { describe, it } from 'node:test';
import assert from 'node:assert';

describe('math', () => {
  it('should add numbers', () => {
    assert.strictEqual(1 + 1, 2);
  });
});

The performance story is also solid. V8 keeps getting faster, and the startup time improvements in recent versions have narrowed the gap with Bun. For most server workloads, Node's performance is not the bottleneck.

Deno 2

Deno made a smart pivot with version 2. Instead of insisting that the Node ecosystem was wrong and everything should use URL imports, Deno 2 added full support for package.json, npm packages, and Node APIs. You can now run most Node.js projects on Deno with minimal changes.

// Deno 2 runs Node packages directly
import express from 'npm:express';

const app = express();
app.get('/', (req, res) => {
  res.json({ runtime: 'deno' });
});
app.listen(3000);

The security model remains Deno's strongest differentiator. By default, your code cannot access the filesystem, network, or environment variables. You grant permissions explicitly. For running untrusted code or building multi-tenant platforms, this is genuinely valuable.

Deno Deploy (the hosting platform) is also compelling. Global edge deployment with zero configuration, built-in KV storage, and tight integration with the runtime. If your deployment target is Deno Deploy, the developer experience is very smooth.

The honest downside: some npm packages still do not work perfectly on Deno, especially those that rely on native addons or Node-specific internals. The compatibility is good, maybe 95%, but that last 5% can be the package you actually need.

Bun

Bun continues to be the speed demon. Package installs are still dramatically faster than npm or pnpm. The bundler is built in and fast. The test runner is fast. Everything about Bun is optimized for raw throughput.

// Bun's HTTP server
const server = Bun.serve({
  port: 3000,
  fetch(req) {
    return new Response('Hello from Bun');
  },
});

console.log('Listening on port ' + server.port);

The Node.js API compatibility has improved significantly since 1.0. Most popular npm packages work out of the box. The SQLite integration is built in, the file I/O is fast, and the Bun.serve() HTTP server handles high concurrency well.

Where Bun still struggles is edge cases. Complex Node.js applications sometimes hit compatibility issues that are hard to debug. The error messages can be less helpful than Node's. And for teams that need long-term stability guarantees, Bun's rapid release cycle can feel risky compared to Node's LTS model.

Benchmarks in Context

Raw HTTP throughput: Bun leads, followed by Deno, then Node. The differences are real but shrinking. In a typical web application where you are waiting on database queries and external APIs, the runtime overhead is a small fraction of the total response time.

Startup time: Bun is fastest (often under 10 milliseconds), which matters for serverless and CLI tools. Node has improved but is still 50 to 100 milliseconds. Deno is comparable to Node.

Package install speed: Bun is 5 to 10 times faster than npm and 2 to 3 times faster than pnpm. If you work on a project with hundreds of dependencies, this saves real time.

TypeScript execution: Both Bun and Deno run TypeScript natively without a compile step. Node requires tsx, ts-node, or the experimental --experimental-strip-types flag. For quick scripts and development, native TypeScript support is a nice quality-of-life improvement.

Which One Should You Use

For production web applications and APIs: Node.js. The ecosystem maturity, LTS support, and operational knowledge base are unmatched. When things go wrong at 3 AM, you want the runtime that has the most Stack Overflow answers and the most people who have debugged the same problem.

For CLI tools and scripts: Bun. The startup time and built-in TypeScript support make it ideal for command-line programs. The all-in-one nature (runtime + bundler + test runner + package manager) means less tooling to configure.

For security-sensitive environments: Deno. The permission model is a real advantage when you need to run third-party code or enforce strict boundaries. Deno Deploy is also excellent if your architecture fits the edge deployment model.

For new projects where you want to experiment: try Bun or Deno. The worst case is that you learn something and can fall back to Node. The best case is that you find a workflow that is genuinely better for your use case.

Is This Sustainable

I think so. The JavaScript ecosystem is large enough to support multiple runtimes, especially when they are converging on compatibility. The competition has been good for developers. Node got faster and added missing features. Deno became more practical. Bun pushed the performance envelope.

The convergence toward Node API compatibility as the common standard means your code is increasingly portable across all three. And that portability is probably the most important outcome of this whole multi-runtime era.