With the new ecommerce API, you can integrate Square’s payment system into your checkout screen just adding a few lines of code. It’s available to users in the US and Canada, and each transaction has a processing fee of 2.9 percent plus 30 cents.
There’s also a new Register API that lets you integrate Square’s service into your own iOS-based point-of-sale app to handle card payments.
With that, Square is going up against the likes of Stripe, Braintree and Paymill. But unlike the rest, its service can be used by brick-and-mortar stores as well. So, if you’re an offline retailer and plan to start selling on the Web, Square might be easier to work with than the competition.