Amazon Payments is a wholly owned subsidiary of Amazon.com that provides means to process transactions online. Launched in 2007, Amazon Payments uses the consumer base of Amazon.com and focuses on giving users the same checkout experience available on “Amazon.com”. It offers two different options for merchants: Checkout by Amazon and Amazon Simple Pay. Checkout by Amazon has the support for both standard and inline payment options. Both of these options can be used for customer payments on your website although the inline option is integrated in your store’s checkout flow. Amazon Simple Pay can be used to receive funds for digital products, games, donations, or other services. In order to complete a purchase using Amazon Payments customers will need to already have or be willing to sign up for an Amazon account. All major credit cards can be used in Amazon’s system if they’re connected to a U.S. billing address.
Yes, the PayPals Rest API can be used by Merchant in 202 countries. It covers most of the countries and to be sure you may look up for your country here: https://www.paypal.com/us/webapps/mpp/country-worldwidePayment Gateways (US) PayPal