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

# Response Format

### API Response Format

All QFPay APIs return JSON-formatted responses. A standard successful response will follow the structure below:

```json theme={null}
{
  "respcd": "0000",
  "respmsg": "success",
  "data": {
    "txamt": "100",
    "out_trade_no": "20231101000001",
    "txcurrcd": "HKD",
    "txstatus": "SUCCESS",
    "qf_trade_no": "9000020231101000001",
    "pay_type": "800101",
    "txdtm": "2023-11-01 10:00:00"
  }
}
```

### Field Description

| Field     | Type       | Description                                                        |
| --------- | ---------- | ------------------------------------------------------------------ |
| `respcd`  | String(4)  | Return code. `"0000"` means success. Other codes indicate failure. |
| `respmsg` | String(64) | Message description of the `respcd` value.                         |
| `data`    | Object     | Contains payment transaction data. See details below.              |

#### Signature Verification

<Note>
  In critical integrations, developers are encouraged to verify the response signature (if present in headers) to ensure data integrity.
</Note>

The response may also include the `X-QF-SIGN` and `X-QF-SIGNTYPE` headers, which can be validated by:

1. Extracting the `data` fields in the same sorted order.
2. Concatenating them into a string with format: `key1=value1&key2=value2&...`
3. Appending the client key.
4. Generating the MD5 hash and comparing it to the received signature.

For the full logic to generate and verify the signature, refer to [Signature Generation](/integration/preparation/authentication-and-signature).