---
title: Sveltekit
description: The build fetches your public policy once and bundles it, so the
  server never fetches it at runtime.
lastModified: "2026-10-10T14:59:21+01:00"
lastAuthor: Kaylee
---
The build fetches your public policy once and bundles it, so the server never
fetches it at runtime.

The [quickstart](/docs/frameworks/sveltekit/quickstart) sets this up across
these files:

|File|Role|
|--|--|
|`vite.config.ts`|`consentManifest` from `@c15t/svelte/vite` fetches the policy.|
|`src/hooks.server.ts`|`c15tHandle()`, whose default mode, `manifest()`, resolves from the fetched policy.|
|`src/routes/+layout.server.ts`|`export { loadConsent as load }` resolves each visitor.|
|`src/routes/+layout.svelte`|`ConsentRoot state={data.consent}` renders the result.|

The plugin's position in `plugins` does not matter. It fetches the policy
once Vite has resolved its config, before anything compiles. Without a
`backendURL` option, it reads `PUBLIC_C15T_BACKEND_URL`, then
`PUBLIC_INTH_PROJECT_URL`, from the environment or `.env`.

The plugin detects the `sveltekit()` plugin and keeps the snapshot on the
server. `loadConsent` and `createConsentRoute()` read it without an import.
The browser bundle never holds it: `ConsentRoot` gets the resolved policy
from `loadConsent` instead.

Static hosts follow [build a static site](/docs/frameworks/sveltekit/rendering#build-a-static-site)
instead.

The snapshot is fixed at build time:

* Rebuild after changing policies, translations or vendors. If your CI caches
  build output, force a fresh build.
* Consent choices still go to the backend.

The build reads the backend URL from your public backend URL variable when
the config doesn't pass one: `NEXT_PUBLIC_C15T_BACKEND_URL` in Next.js,
`NUXT_PUBLIC_C15T_BACKEND_URL` in Nuxt, `PUBLIC_C15T_BACKEND_URL` in Astro,
Svelte and SvelteKit, and `VITE_C15T_BACKEND_URL` in TanStack Start and other
Vite apps. Each also reads the matching Inth variable, such as
`NEXT_PUBLIC_INTH_PROJECT_URL`, when the c15t one is unset. See
[set the backend URL](/docs/concepts/modes#set-the-backend-url).

The fetch waits at most 10 seconds. When it fails, or no backend URL is set,
every framework does the same thing:

|Command|Default when the fetch fails|
|--|--|
|Production build: `next build`, `vite build`, `nuxt build`, `astro build`|The build stops with an error.|
|Dev: `next dev`, `vite dev`, `nuxt dev`, `astro dev`|A warning, and the server fetches the policy at runtime.|

Set `onBuildError` to use one behaviour for both. `'fail'` stops dev too.
`'runtime'` lets a production build finish, and the server fetches the policy
at runtime. The `C15T_ON_BUILD_ERROR` environment variable overrides the
option, so you can deploy during a backend outage without a code change:

```sh
C15T_ON_BUILD_ERROR=runtime npm run build
```

Turborepo's strict environment mode hides undeclared variables from tasks, so
list `C15T_ON_BUILD_ERROR` in the build task's `passThroughEnv` there.

The build skips the fetch, without an error, when it can't use a snapshot,
for example when the backend URL is relative. With `onBuildError: 'fail'`, a
relative URL stops the build. [Consent modes](/docs/concepts/modes#what-happens-when-the-download-fails)
lists every case.

`vite build` and `vite dev` fetch the manifest when they start. `vite preview`
serves the last build without fetching. The plugin writes no file into your
app, so there is nothing to keep out of Git. `c15t/generated` ships its own
types, so `tsc`, `vue-tsc` and `svelte-check` pass on a fresh checkout without
a build first.

The plugin can't see the options your app passes to `manifest()`. When the
app passes `source: 'runtime'` or `manifestURL`, set
`consentManifest({ source: 'runtime' })` too. The build then downloads no
manifest, so it doesn't fail when the backend's `/manifest` is down.

On SvelteKit 3, `svelte-kit sync` resolves the Vite config, so it runs the
plugin and fetches the policy too, following the same rules when the fetch
fails. SvelteKit 2.68 also runs the plugin during `svelte-kit sync`, but logs
a failed fetch and continues.

To apply policy edits without a rebuild, set
`c15tHandle({ mode: manifest({ source: 'runtime' }) })` and follow
[fetch the manifest at runtime](/docs/frameworks/sveltekit/rendering#fetch-the-manifest-at-runtime).
To have the backend resolve every visit instead, set
`c15tHandle({ mode: hosted() })`. The layout load then calls the backend's
`/init`, and so does the browser on pages the server did not resolve.