Frequently Asked Questions :)
To accept card payments and use a payment gateway to transmit online payment data, you need to have a merchant account.
We would suggest to have low cost payment gateways with proper knowledge of hidden costs if any. The payment gateway should be approved by the central bank and should be abided by security standards.
The API works as an application transmits a message/request to the API, which relays it to the payment processing network, which in turn processes the request and responds to the API, which then relays the response to the application.