---
title: "SvelteKit Adapter"
description: "Use oRPC inside a SvelteKit project by mounting a handler in an endpoint."
sidebar:
  label: "SvelteKit"
---

[SvelteKit](https://svelte.dev/docs/kit/introduction) is a framework for rapidly developing robust, performant web applications using Svelte. Its endpoints follow the [Fetch API](https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API), so oRPC integrates through the [Fetch API Adapter](/docs/adapters/fetch-api).

## Server

```ts title="src/routes/rpc/[...rest]/+server.ts"
import type { RequestHandler } from './$types'
import { onError } from '@orpc/server'
import { RPCHandler } from '@orpc/server/fetch'

const handler = new RPCHandler(router, {
  interceptors: [
    onError((error) => {
      console.error(error)
    }),
  ],
})

const handle: RequestHandler = async ({ request }) => {
  const { response } = await handler.handle(request, {
    prefix: '/rpc',
    context: {} // Provide initial context if needed
  })

  return response ?? new Response('Not found', { status: 404 })
}

export const GET = handle
export const POST = handle
export const PUT = handle
export const PATCH = handle
export const DELETE = handle
```

:::info
The `handler` can be any supported oRPC handler, such as [RPCHandler](/docs/rpc/handler), [OpenAPIHandler](/docs/openapi/handler), or another custom handler.
:::

## Optimize SSR

To reduce HTTP requests and improve latency during SSR, you can utilize [Svelte's special `fetch`](https://svelte.dev/docs/kit/web-standards#Fetch-APIs) during SSR. Below is a quick setup, see [Optimizing SSR](/docs/recipes/optimizing-ssr) for more details.

<CodeGroup>

```ts title="src/lib/orpc.ts"
import type { RouterClient } from '@orpc/server'
import { createORPCClient } from '@orpc/client'
import { RPCLink } from '@orpc/client/fetch'

if (import.meta.env.SSR) {
  await import('./orpc.server')
}

declare global {
  var $client: RouterClient<typeof router> | undefined
}

const link = new RPCLink({
  url: '/rpc',
  origin: () => {
    if (typeof window === 'undefined') {
      throw new Error('This link is not allowed on the server side.')
    }

    return window.location.origin
  },
})

/**
 * Fall back to a browser client when no SSR client is registered.
 */
export const client: RouterClient<typeof router> = globalThis.$client ?? createORPCClient(link)
```

```ts title="src/lib/orpc.server.ts"
import type { RouterClient } from '@orpc/server'
import { getRequestEvent } from '$app/server'
import { createORPCClient } from '@orpc/client'
import { RPCLink } from '@orpc/client/fetch'

if (typeof window !== 'undefined') {
  throw new Error('This file should only be imported on the server')
}

const link = new RPCLink({
  url: '/rpc',
  origin: () => getRequestEvent().url.origin,
  fetch: (url, init) => getRequestEvent().fetch(url, init),
})

const serverClient: RouterClient<typeof router> = createORPCClient(link)
globalThis.$client = serverClient
```

</CodeGroup>