# Bun runtime now in Public Beta for Vercel Functions

**Published:** October 28, 2025 | **Authors:** Tom Lienard, Javi Velasco, Jeff See

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The Bun runtime is now available in Public Beta for Vercel Functions.

You can choose between Node.js and Bun as your project runtime, selecting the best option for your workload.

[Benchmarks show Bun reduced average latency by 28%](https://vercel.com/blog/bun-runtime-on-vercel-functions#benchmark-results) for CPU-bound Next.js rendering compared to Node.js.

To use Bun in Vercel Functions, set the runtime globally in your project's `vercel.json`:

**vercel.json**
```json
{
  "bunVersion": "1.x"
}
```

We currently support the following frameworks, with more on the way:

- `Next.js`
- `Hono`
- `Express`
- `Nitro`

Bun supports TypeScript with zero configuration. Here's an example with Hono:

**src/index.ts**
```typescript
import { Hono } from 'hono';
const app = new Hono();
app.get('/', (c) => {
  return c.text(`Hello from Hono on Bun ${process.versions.bun}!`);
});
export default app;
```

Or get started with one of our starter templates:

- [Express on Bun](https://vercel.com/templates/backend/express-on-bun)
- [Hono on Bun](https://vercel.com/templates/backend/hono-on-bun)

Bun deployments automatically integrate with Vercel's existing logging, observability, and monitoring systems.

See [benchmarks in our blog post](https://vercel.com/blog/bun-runtime-on-vercel-functions), or [read the docs to learn more](https://vercel.com/docs/functions/runtimes/bun).

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📚 **More updates:** [View all changelog entries](/changelog/sitemap.md) | [Blog](/blog/sitemap.md)