> ## Documentation Index
> Fetch the complete documentation index at: https://docs.qanapi.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Custom Headers

> Unique headers used in API v3 to control authentication, data selection, and request routing.

# Authentication Header

<ParamField header="X-Qanapi-Authorization" type="string" required>
  Your unique API key. All v3 API keys are prefixed with `qapi_`.
</ParamField>

<Tip>
  You can manage and rotate your API keys in the [API Keys section](/api-reference/list-api-keys).
</Tip>

# Content Control

<ParamField header="Content-Type" type="string" required>
  Must be set to `application/json` for all requests containing a JSON payload.
</ParamField>

<ParamField header="X-Qanapi-Fields" type="string">
  A comma-separated list of fields in the JSON payload to be processed (encrypted or decrypted).

  <Info>
    This header is **required** for encryption and decryption requests. For other API calls, it can be omitted.
  </Info>

  **Dot Notation:** You can use dot notation to target nested fields within multi-dimensional objects.
</ParamField>

## Dot Notation Example

When working with nested JSON structures, use the `X-Qanapi-Fields` header to specify exactly which fields should be
touched.

```bash Request theme={null}
curl -X POST https://{subdomain}.qanapi.cloud/api/v3/encryption/{proxy}/encrypt \
  -H "X-Qanapi-Authorization: qapi_..." \
  -H "X-Qanapi-Fields: user.email, user.address.zip" \
  -d '{
    "user": {
      "name": "John Doe",
      "email": "john@example.com",
      "address": {
        "city": "New York",
        "zip": "10001"
      }
    }
  }'
```

# Advanced Routing

<ParamField header="X-Qanapi-Destination" type="string">
  A URL to forward the request to after processing. If provided, Qanapi will act as a transparent proxy.
</ParamField>

<Warning>
  When using `X-Qanapi-Destination`, all non-Qanapi headers (e.g., `Authorization`, `Custom-App-Header`) will be
  forwarded to the destination URL along with the processed payload.
</Warning>

<Card title="Try it out" icon="vial" href="/v3/encryption/{proxy}/encrypt">
  See these headers in action by testing the Encryption endpoints.
</Card>