kiln 🔥

Compile framework apps into a single native executable via Bun.

Supported: Next.js · Planned: React Router, SvelteKit, TanStack Start, Deno runtime

Install

npm install kiln
# or
bun add kiln

Quick Start (Next.js)

1. Configure the build adapter

import type { NextConfig } from "next";

const nextConfig: NextConfig = {
  experimental: {
    adapterPath: import.meta.resolve("kiln"),
  },
};

export default nextConfig;

2. Build & compile

next build && kiln

3. Run the binary

./server          # single file, no node_modules needed

CLI

kiln [options] [-- bun-build-flags...]

| Flag | Default | Description | |---|---|---| | --project, -p | . | Project root directory | | --out, -o | ./server | Output binary path | | --framework, -f | (auto-detect) | Framework adapter to use | | --list-adapters | | Show registered adapters |

Cross-compilation

kiln -o ./server-linux   --target bun-linux-x64
kiln -o ./server-arm     --target bun-linux-arm64
kiln -o ./server-win.exe --target bun-windows-x64

transpilePackages (Next.js)

The Next.js adapter automatically detects packages that need to be transpiled (e.g., UI libraries in a monorepo). It looks for them in this order:

1. Standard Next.js transpilePackages in next.config.js (see docs)
2. Custom nextConfig.nextRuntimeCompiler.transpilePackages
3. Environment variable NEXT_RUNTIME_COMPILER_TRANSPILE_PACKAGES (comma-separated)

Example next.config.js:

/** @type {import('next').NextConfig} */
const nextConfig = {
  transpilePackages: ['@repo/ui-components', '@repo/design-system'],
}

module.exports = nextConfig

CDN / assetPrefix

When assetPrefix is set, static assets (/_next/static/*) are assumed CDN-hosted and not embedded. public/* is always embedded.

Adding a New Framework Adapter

Implement the FrameworkAdapter interface and register it:

import type { FrameworkAdapter } from "kiln";
import { registerAdapter } from "kiln";

const myAdapter: FrameworkAdapter = {
  framework: "my-framework",
  name: "My Framework",
  detect: (dir) => existsSync(join(dir, "my-framework.config.ts")),
  getStandaloneDir: (dir) => join(dir, "build/server"),
  getDistDir: (dir) => join(dir, "build"),
  getStaticAssetConfig: () => ({ dir: "client", urlPrefix: "/assets" }),
  getStubs: () => [],
  getBuildDefines: () => [],
  generateServerEntry: (ctx) => `/* runtime entry code */`,
};

registerAdapter({ framework: "my-framework", create: () => myAdapter });

Programmatic API

import { compileApp, compileStandalone, generateEntryPoint } from "kiln";

| Function | Description | |---|---| | compileApp(opts) | End-to-end: detect framework → generate → compile | | generateEntryPoint(opts) | Generate asset map + server entry using adapter | | compileStandalone(opts) | Run bun build --compile only |

Acknowledgements

The Next.js compilation logic in this project was heavily inspired by and derived from next-bun-compile. A huge thanks to the author for paving the way for running standalone Next.js apps natively in Bun!