The Authorize.net PHP SDK by Authorize.net allows to implement API authorization features into applications, useful to verify payments with credit cards. Developers can benefit from the three steps available on the official site, that include to import the SDK, create a new PHP file for a transaction, and run the program.
Google has introduced a one-click payment experience via a new Payment Request API. The API eliminates the need for a traditional checkout experience by handling the payment experience through a simple API call. The service is not a payment method, nor does it integrate with payment processors.