# Headers

Echo back the request headers your client actually sent to Market Data. Useful for debugging proxies, custom header plumbing, or verifying the User-Agent the SDK is presenting.

The `Authorization` header is redacted server-side before the response is returned.

## Making Requests

Use the `headers()` method on the `utilities` resource.

| Output Format          | Result Payload    | Description                                    |
|------------------------|-------------------|------------------------------------------------|
| **internal** (default) | `HeadersResponse` | Map of header name to value as the API saw it. |
| **json**               | Raw JSON object   | The raw response as returned by the API.       |

<a name="headers"></a>
## headers

```typescript
headers(): MarketDataPromise<HeadersResponse>
```

Fetches the request-header echo. Takes no parameters.

#### Returns

- [`MarketDataPromise<HeadersResponse>`](https://www.marketdata.app/docs/sdk/js/client#MarketDataPromise)

### Default

```typescript
import { MarketDataClient } from "@marketdata/sdk";

const client = new MarketDataClient();

try {
  const h = await client.utilities.headers();
  console.log(h["user-agent"]);   // "marketdata-sdk-js/1.0.0"
  console.log(h["accept-encoding"]);
} catch (error) {
  console.error(error);
}
```

<a name="HeadersResponse"></a>
## HeadersResponse

```typescript
type HeadersResponse = Record<string, unknown>;
```

A bag of header name → value pairs. Header names are lowercased; values may be strings or arrays of strings depending on whether the header was sent multiple times.

> [!TIP]
> Use this to confirm what gets through when you wire the SDK behind a corporate proxy or add custom headers via your runtime's `fetch` interception.