This page explains how to deploy and run your background jobs on the Defer Platfom using the Bun runtime instead of Node.js.

If you are looking to use Bun only as a package manager, please refer to Node.js supported package managers

Runtime & client compatibility

Prior to version 1.11.0, the @defer/client is not compatible with Bun. Please update your client to a version greater than or equal to 1.11.0 to use the Bun runtime.

Setup runtime

Only versions 1.x are supported.

To use the Bun runtime, add the following in the engines field of your package.json as follows:

  "engines": {
    "bun": "1.x"


The Bun package manager is the only one supported on the Bun runtime on the Defer platform.

Here aren the details of the package manager and its corresponding installation command ran upon deploy.

LockfilePackage ManagerCommand
bun.lockbBunbun install --frozen-lockfile

Dependencies are installed with the exact versions found in the lockfile