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.
PublicAPIs - Explore the largest API directory in the galaxy
TrueLayer - Simple Bank APIs to access real-time financial data
Teller API - A single API to connect your app with any bank's account
Dwolla - Dwolla powers innovations with sophisticated account-to-account payment solutions.
Tilisy API - Free access to European bank accounts for developers