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Vercel is a cloud platform for building, deploying, and scaling apps.
The Bun runtime is in Beta. Some features are not yet supported — for example, automatic source maps, byte-code caching, and metrics on node:http/https.
Bun.serve is not supported on Vercel Functions. Use Bun with frameworks supported by Vercel, like Next.js, Express, Hono, or Nitro.
1

Configure Bun in vercel.json

To enable the Bun runtime for your Functions, add a bunVersion field in your vercel.json file:
vercel.json
Vercel automatically detects this configuration and runs your application on Bun. The value must be "1.x"; Vercel handles the minor version internally.For best results, match your local Bun version with the version used by Vercel.
2

Next.js configuration

If you’re deploying a Next.js project (including ISR), update your package.json scripts to use the Bun runtime:
package.json
The --bun flag runs the Next.js CLI under Bun. Bundling (with Turbopack or Webpack) is unchanged.
With these scripts, both local development and builds use Bun.
3

Deploy your app

Connect your repository to Vercel, or deploy from the CLI:
terminal
Or install the Vercel CLI globally:
terminal
Learn more in the Vercel Deploy CLI documentation →
4

Verify the runtime

To confirm your deployment uses Bun, log the Bun version:
index.ts
See the Vercel Bun Runtime documentation for feature support →
  • Fluid compute: Both Bun and Node.js runtimes run on Fluid compute and support the same core Vercel Functions features.
  • Middleware: To run Routing Middleware with Bun, set the runtime to nodejs:
middleware.ts