@freshcells/next-static-components

Experimental. Render parts of a Next.js application (e.g. Header & Footer) as standalone bundles for embedding into third-party applications. Backed by Vite for the build, Next.js for the runtime API route.

Install

yarn add @freshcells/next-static-components vite @vitejs/plugin-react-swc

Requirements

• next ≥ 16
• vite ≥ 8 (uses rolldown)
• @vitejs/plugin-react-swc ≥ 4
• node ≥ 18
• react, react-dom ≥ 18 (the build uses your hoisted React, not Next.js's bundled copy)

Quick start

1. Add .next-static/ to .gitignore.

2. Create next-static.config.mjs in your project root (next to next.config.mjs).

3. Add scripts:

   {
     "scripts": {
       "build-static": "next-static-components",
       "build-static-dev": "next-static-components dev"
     }
   }

4. Create a catch-all API route (pages/api/static/[...slug].ts or App Router equivalent) wired to serve().

Configuration: next-static.config.mjs

The CLI loads next-static.config.mjs (or .js) from the directory you run it in. defineConfig is just an identity helper for IDE typing — the file can also export a plain object.

// @ts-check
import { defineConfig } from '@freshcells/next-static-components'

export default defineConfig({
  entry: './static-page/entrypoint.tsx',
  importExcludeFromClient: ['../graphql-cache'],
  cssExtendFolders: ['../../../packages/shared/styles/extend'],
  alias: [
    { find: '~fonts', replacement: './src/fonts' },
    { find: '~@images', replacement: './src/images' },
  ],
  additionalData: `$icomoon-font-path: '~fonts/iconfont/fonts';`,
  ssrExternal: ['i18n-iso-countries'],
})

Option	Type	Description
entry	string (required)	Path to your entrypoint file (the @main module), relative to project root.
importExcludeFromClient	string[]	Specifiers replaced with an empty module on the client build only. The SSR build keeps the real implementation. Use for server-only code that the client never needs (e.g. graphql codegen output).
cssExtendFolders	string[]	Folders that mirror node_modules. For each .scss file imported from node_modules/<pkg>/<path>.scss, if <extendFolder>/<pkg>/<path>.scss exists it gets appended via @import. Equivalent to the webpack-css-import-inject-loader chain.
alias	{find, replacement}[]	Extra import + CSS url() aliases. find may be a string or RegExp. Webpack-style ~pkg references are stripped automatically — you only need entries here for project-specific paths like ~fonts, ~@images. Relative replacements are resolved against the project root.
additionalData	string	Raw SCSS prepended to every Sass entry. Concatenated after the consumer's next.config.sassOptions.additionalData, so this is where project-specific variable overrides go (e.g. $icomoon-font-path: '...';).
ssrExternal	string[]	Extra packages to mark as external on the SSR build. The defaults (next, react, react-dom, react-dom/server) are always external; add packages that fail to bundle (typically dynamic-require() deps like i18n-iso-countries).

Auto-derived from next.config.mjs

The build reads these fields from your existing next.config.{mjs,js,cjs,ts} so you don't have to duplicate them:

• i18n — locales, defaultLocale, domains
• basePath
• experimental.swcPlugins — fed to @vitejs/plugin-react-swc
• sassOptions.additionalData — string prepended to every Sass entry
• sassOptions.loadPaths — Sass @import resolution roots
• sassOptions.silenceDeprecations — Sass deprecation warning filter

There are no in-package defaults for these — Sass behavior matches whatever your next.config.mjs already declares. Override or add anything else via next-static.config.mjs.

CLI

next-static-components            # production build
next-static-components dev        # watch + dev React

Flag	Description
--dev	Force development React (unminified errors + dev assertions on the client). Implied by the dev subcommand.
--cacheSuffix=<name>	Use .next-static/cache/vite-<name> as the Vite cache directory. Useful for parallel build variants.

The dev subcommand runs vite build --watch for both client and SSR. Output filenames are stable (no hashes) and unminified, with inline JS sourcemaps. Rebuilds are picked up by the next request to /api/static/render — no Next.js dev-server restart, just a browser refresh.

Entrypoint

A single file declares all components, props, optional wrapper, and head content.

import React from 'react'
import type { Entrypoint, WrapperProps } from '@freshcells/next-static-components'

interface Context {
  someData: string
}
interface Props {
  someData: string
}

const Header = (props: Props) => <p>My Header</p>
const Footer = (props: Props) => <p>My Footer</p>

const entry: Entrypoint<Props, Context> = async (context) => ({
  props: context,
  components: [Header, Footer],
  wrapper: function Wrapper({ components }: WrapperProps) {
    const [header, footer] = components
    return (
      <div>
        {header}
        <div>something in between</div>
        {footer}
      </div>
    )
  },
  additionalHeadElement: <title>A title</title>,
})

export default entry

Next.js API route

// pages/api/static/[...slug].ts
import { serve } from '@freshcells/next-static-components'

export default serve(async (req, res) => ({ someData: 'myValue' }), {
  assetPrefix: 'https://your-cdn.example.com',
  linkPrefix: 'https://your-main-domain.example.com',
  locale: 'de-de',
})

Option	Description
assetPrefix	URL prefix for emitted assets (CDN host). Empty = relative URLs.
linkPrefix	URL prefix used by useRouter().push() and link generation.
locale	Locale to render. Falls back to next.config.mjs's defaultLocale.
outputMode	'html' (default), 'jsonp', or (req, res, { styles, head, content, scripts }) => void for embedding into another framework's response.

The second argument can also be a function — useful when options depend on req:

export default serve(
  async (req) => ({
    /* context */
  }),
  async (req) => ({
    locale: (req.query.locale as string) ?? 'en-gb',
    linkPrefix: 'https://some-domain.example.com',
  }),
)

Run yarn build-static, start Next.js (yarn dev or yarn start), and navigate to /api/static/render.

Dev workflow

Two terminals:

yarn build-static-dev   # rebuilds client + SSR on every save
yarn dev                # Next.js dev server (handles the API route)

Edit a .tsx / .scss → terminal A reports built in Xms → refresh the browser. SSR-side changes are picked up on the next request without restarting Next.js (mtime-keyed module reload).

Detecting the static build

process.env.IS_NEXT_STATIC_BUILD === '1' is set during the build and dev watcher. Branch on it from next.config.mjs if needed.

Restrictions

Router

The client-side Next.js router singleton is not initialized. useRouter() returns a context-backed mock with read-only properties (route, pathname, query, locale, …) and a push() that performs a full navigation via location.href.

import Router from 'next/router' // ❌ no-op default export
import { useRouter } from 'next/router' // ✅

next/head

Runtime head modification is not supported. Use additionalHeadElement on the entrypoint to inject head content at SSR time.

next/dynamic

Backed by React.lazy + Suspense. Streaming SSR (renderToPipeableStream with onAllReady) waits for every Suspense boundary, so the rendered HTML contains the resolved content.

Only dynamic as the import name is supported:

import dynamic from 'next/dynamic' // ✅

The build instruments every dynamic(() => import('./X')) callsite to record which lazy boundaries actually rendered, so the SSR HTML preloads only the chunks that streamed (no FOUC, no shipping CSS for unrendered branches).

next/image

Image-file imports return { src, width, height, blurDataURL } — the StaticImageData shape next/image expects. The next/image component itself is not shimmed; it uses your hoisted Next.js copy at runtime.