Meet bunfig

Chris Breuer · July 11, 2026

Every tool needs configuration, and every tool author ends up writing the same loader: find the config file, support several file names and extensions, merge user values over defaults, and keep TypeScript types intact. bunfig is that loader, extracted once and done properly for Bun.

How it works

import { loadConfig } from 'bunfig'

interface MyLibConfig {
  port: number
  verbose: boolean
}

const config = await loadConfig<MyLibConfig>({
  name: 'my-lib',
  defaults: { port: 3000, verbose: false },
})

bunfig resolves my-lib.config.ts (or .js, .mjs, .json, and dotfile variants), deep-merges what it finds over your defaults, and returns a fully typed object. Your users write configs in TypeScript with autocomplete; you write zero resolution logic.

Small on purpose

There is no plugin system, no schema DSL, no validation framework. It loads config files fast and predictably, and that is the whole job. Nearly every stacksjs tool (rpx, tlsx, dtsx, and the framework itself) loads its config through bunfig, which keeps the config experience identical across the ecosystem.

Grab it at github.com/stacksjs/bunfig.