Google Payment API - Enable an easy-to-use checkout experience for customers

Braintree - An all-in-one solution to accept, process, and split payments in your mobile app or online - from small business to large enterprise.

Giftbit Payment API - Stripe for gift cards

ProPay - ProPay is a multiple payment making service provider that lets its users to make payment to anyone in any part of the world.

Stripe - Online payment processing for internet businesses. Stripe is a suite of payment APIs that powers commerce for online businesses of all sizes. Use Stripe’s payment platform to accept and process payments online for easy-to-use commerce solutions.

XE.com - XE.com Inc. (XE) is a Canadian online foreign exchange services company.