This guide describe payment method creation based on Payment Offsite API

Express Lane is one of the newest Drupal e-commerce platforms. It provides streamlined integration for PayPal Express Checkout. It's intended for easy configuration, yet it's powerful enough to use as the e-commerce or e-fundraising platform that will grow with your organization.

Payment Gateway API this is the plugable module that provide API for payments on Drupal site. This module will be useful to those who do not need the full functionality of a shopping cart, but need to do accept payments online. For example: donations, pay for access to content, the simple site sells only a single product, etc.

Payment methods

Now module provides access to the following payment gateways:

Payment is a fully pluggable and reusable platform for processing payments. Modules implementing it and payment methods are completely unaware of each other, which means that any module can use any payment method plugged into Payment and vice versa.
This handbook section describes the thoughts behind and the workflow of the Payment project, which is useful for site builders and developers.