Adapters and deployment

For the site to work beyond your computer, the project is built with npm run build. The result depends on where the site will run: on a server with Node.js, on a cloud platform or as a set of static files. For each target there is an adapter — a package that turns the SvelteKit build into the needed format.

The default adapter

A project from sv is already set up with adapter-auto:

// svelte.config.js
import adapter from '@sveltejs/adapter-auto';
 
const config = {
  kit: {
    adapter: adapter()
  }
};
 
export default config;

adapter-auto detects popular platforms — Vercel, Netlify, Cloudflare — and uses the right adapter when building there. For your own server you choose the adapter explicitly.

Your own server: adapter-node

Install the adapter:

npm install -D @sveltejs/adapter-node

And replace the import in the settings:

// svelte.config.js
import adapter from '@sveltejs/adapter-node';
 
const config = {
  kit: {
    adapter: adapter()
  }
};
 
export default config;

Now build and start the project:

npm run build
node build

The build appears in the build folder, and node build starts the server. The terminal shows an address — by default http://localhost:3000 — and the blog opens with its forms and API. The port is changed with an environment variable: PORT=8080 node build.

A static site: adapter-static

If a site has no server part — no form actions, no +server.js — it can be built into plain HTML files and put on any hosting:

npm install -D @sveltejs/adapter-static

In svelte.config.js import @sveltejs/adapter-static, and in the root layout enable prerendering of all pages:

// src/routes/+layout.js
export const prerender = true;

After npm run build the build folder contains ready HTML files for every page.

Which adapter to choose

Before publishing, check the build locally: npm run preview runs the built version.

Common mistake

Choosing adapter-static for a blog with forms and an API. Actions from +page.server.js and +server.js files need a running server, while a static site is only files. The build stops with an error about pages that cannot be prerendered. Such a site needs adapter-node or a cloud platform adapter.