# Data transfer

In order to ensure a secure data transfer during the cooperation with Ratepay, please transfer your data to Ratepay's server via SFTP.

Several regular customer files (.csv) can be added to one .zip file and uploaded to Ratepay's server by SFTP.

If you have several Shop IDs, they must be uploaded separately and must not be stored in the same ZIP file.

Whenever a new regular customer file is uploaded to the SFTP server, the **data of the previously uploaded files is removed!**

**Therefore, please note to submit your complete customer history with each upload!**

Please ensure to transmit your **complete** payment history of your regular customers on a **certain time interval**!

After you have uploaded a regular customer file, then you can transmit the customer identifier in the...

[PAYMENT_REQUEST](/docs/developer/api_integration/payment_1.8/payment_api_documentation/the_ratepay_gateway_operations/place_order/payment_request/) call (for Payment API 1.8; as parameter [merchant-consumer-id](/docs/developer/api_integration/payment_1.8/payment_api_documentation/api_explorer/head/external/merchant-consumer-id/) in the [External-Block](/docs/developer/api_integration/payment_1.8/payment_api_documentation/api_explorer/head/external/))

or

[Authorize transaction](/apis/payment/openapi/payment_api/transaction-management/createtransaction) call (for Payment API 2.0; as parameter [shop-buyer-id](/apis/payment/openapi/payment_api/transaction-management/createtransaction#!path=buyer/shop_buyer_id))

...to benefit from the regular customer concept.

Please upload the regular customer file(s) to: `/to_ratepay/known_customers/`