> Index of every page on this site: [llms.txt](https://kubb.dev/llms.txt)

# Add interceptors

Register handlers on `client.interceptors.request`, `.response`, or `.error` to apply behavior across calls. Handlers receive the resolved request and result objects.

## Run before the send

Request handlers run after URL construction, serialization, and authentication. Return the modified request:

```typescript
import { client } from './gen/.kubb/client'

client.interceptors.request.use((request) => {
  request.headers['X-Request-ID'] = crypto.randomUUID()
  return request
})
```

The handler receives a `ResolvedRequest` (`url`, `method`, `headers`, `body`, `signal`,
`credentials`, `options`, `responseType`).

## Run after the send

Response handlers run before calls resolve, and before the status split and deserialization, so
`data` is the raw body. The handler receives a `TransportResult` (`data`, `status`, `statusText`,
`headers`, `contentType`, `request`, `response`):

```typescript
client.interceptors.response.use((result) => {
  console.info(`${result.status} ${result.request.url}`)
  return result
})
```

## React to an error

Use an error handler to react to HTTP errors on the throwing path. The handler receives the
`ResponseError`:

```typescript
client.interceptors.error.use((error) => {
  if (error.status === 401) scheduleTokenRefresh()
  return error
})
```

This channel only fires on the throw path. When you read with `throwOnError: false`, a documented
non-2xx response resolves and no error interceptor runs, so inspect the returned `error` on the
result instead. A transport failure (no response) still throws. The error handler does not run,
because there is no result to pass it.

## Add, replace, and remove handlers

`use` registers a handler and returns an id. Pass that id to `eject` to remove it, or to `update`
to swap its function in place.

> [!NOTE]
> Handlers run in the order you register them.

```typescript
const id = client.interceptors.request.use((request) => request)

client.interceptors.request.update(id, (request) => {
  request.headers['X-Trace'] = 'on'
  return request
})

client.interceptors.request.eject(id)
```

## Where to set them

Register handlers on the shared `client` for all operations, or on a separate `createClient` instance for isolated calls. Interceptors are instance-level settings.

## Sitemap

See the full [sitemap](https://kubb.dev/sitemap.md) for all pages.