It's for a Point of Sale Terminal where the customer will bring the physical credit card and it will be swiped through the terminal. The business has a merchant account on some banks. So, how do I start accepting credit cards in my app? The credit cards that needs to be accepted include: visa, master-card, amex, discover. Which APIs do I need to use? The programming language doesn't matter it can be in any programming languages Java/C#/C++/Python or anything. Will there be a single API or multiple APIs that need to be integrated? (I know some about PCI compliance and security encryption)