# Rollup, Rolldown and tsdown (/docs/bundlers/rollup)

## Rollup [#rollup]

Rollup doesn't know whether it builds for the browser or a server, so the plugin defaults to the
[browser target](/docs/browser-builds). Set `target: 'server'` for a server bundle:

```js title="rollup.config.js"
import tyfigo from 'tyfigo/rollup';

export default {
	input: 'src/server.js',
	output: { file: 'dist/server.mjs', format: 'es' },
	external: ['tyfigo/runtime'],
	plugins: [tyfigo({ target: 'server' })],
};
```

## Rolldown [#rolldown]

Rolldown's `platform` picks the target: `node` is a server build, `browser` (or `neutral`) a browser build.

```js title="rolldown.config.js"
import tyfigo from 'tyfigo/rolldown';

export default {
	input: 'src/server.ts',
	platform: 'node',
	output: { file: 'dist/server.mjs', format: 'es' },
	plugins: [tyfigo()],
};
```

## tsdown [#tsdown]

tsdown takes Rolldown plugins, and builds for `node` by default:

```ts title="tsdown.config.ts"
import { defineConfig } from 'tsdown';
import tyfigo from 'tyfigo/rolldown';

export default defineConfig({
	entry: ['src/main.ts'],
	plugins: [tyfigo()],
});
```

None of these have a mode. A browser build uses `NODE_ENV` at build time, and a server build inlines every environment's layer
files and picks them by `NODE_ENV` when it runs ([Server bundles](/docs/browser-builds#server-bundles)), unless you pass
`environment`. A server build reads `.env` files and environment variables when it runs, through `tyfigo/runtime`; keep that
import external when the bundle runs next to an installed `tyfigo`.