For merchants doing custom development, Authorize.Net offers multiple methods of direct Integration to the Gateway. These are for merchants NOT using a pre-integrated Shopping Cart or POS.

Here is a link to the Developer Playbook.

Here is a link to the Developer API Reference Guide.

Authorize.Net offers toll-free technical support at 877.447.3938 and supports more Shopping Carts and Point of Sale solutions than any other payment gateway.

Included:

NO Set Up Fees

NO Cancellation Fees

FREE Tech Support

FREE Virtual Terminal

FREE Online Reporting

FREE Recurring Billing

FREE Invoicing

FREE Tokenization CIM

FREE Developer APIs

FREE Cart Integration