eWAY lets WHMCS users to accept online credit card payments easily and securely.
The F2B payment gateway module is available in WHMCS.
Forte is a payment gateway module in WHMCS.
Gate2Shop is a payment gateway module in WHMCS.
GoCardless automates electronic direct debit payments.
iDeal via Mollie is a payment gateway in WHMCS.
The inpay payment gateway module is available in WHMCS.