> For the complete documentation index, see [llms.txt](https://prepaidify.gitbook.io/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://prepaidify.gitbook.io/docs/virtual-card/api-integration/things-need-to-know.md).

# Things Need To Know

### About Header

Request Header

| Parameter            | Mandatory | Type   | Description               |
| -------------------- | --------- | ------ | ------------------------- |
| ach-access-key       | Y         | string | key                       |
| ach-access-sign      | Y         | string | signature                 |
| ach-access-timestamp | Y         | string | UTC millisecond timestamp |
| email                | Y         | string | Exp.54158788645\@gmail    |
| language             | N         | string | EN/CH/JA                  |

### Reverse Validation Instructions

To ensure security, a reverse validation process is required for each transaction operation. The request-response should return "success" and the response header should include verification of the signature. Please refer to the specific guidelines on signature for details.

For merchant onboarding, it is necessary to provide a list of reverse transaction addresses, including:

1. Recharge reverse validation address
2. Refund reverse validation address
3. Card creation reverse validation address
4. Card cancellation reverse validation address

#### Example

Request URL: "/**/**/createCheck"

Request Method: GET

Request Parameter:

| Parameter | Type   | Description  |
| --------- | ------ | ------------ |
| orderNo   | string | order number |

### IP Whitelist

To ensure security, IP identification is required for each operation. The following data needs to be provided:

Accessing merchants need to provide a list of IP addresses:

192.168.1.123\
192.168.1.124\
192.168.1.125\
These IP addresses represent the allowed sources from which the merchants can access and perform operations.