1) Square, because they have no fixed fee per transaction. 2.75% means 27.5c per $10 charge. It's not really something you integrate with an app, but with talking of swiping, it's not clear what the use case is.
2) PayPal micropayments. At 5% + $0.05, it's 55c per $10 charge. PayPal has a card-swipe reader the same as Square, but people can also pay with their PayPal accounts, or you can take full control over the payment interface by implementing the PayPal Pro API in your app.
Both are less than the 2.9% + $0.30 offered by Stripe, Braintree, or most any low volume MOTO merchant account.
I don't think anyone can recommend what the best input method is without any knowledge of what your app is or who your customers will be.
Because Square is not a MOTO processor, it's a card-present processor. You can't use Square to take payments on a website. The interchange fees for card-present transactions are less than 1/2 the average fees for card-not-present transactions. If they're paying 1% but charging you 2.75%, that easily covers the fixed fee you're comparing to.
They shouldn't be compared to PayPal, Stripe, etc. but to the standard merchant accounts brick-and-mortar stores get.
1) Square, because they have no fixed fee per transaction. 2.75% means 27.5c per $10 charge. It's not really something you integrate with an app, but with talking of swiping, it's not clear what the use case is.
2) PayPal micropayments. At 5% + $0.05, it's 55c per $10 charge. PayPal has a card-swipe reader the same as Square, but people can also pay with their PayPal accounts, or you can take full control over the payment interface by implementing the PayPal Pro API in your app.
Both are less than the 2.9% + $0.30 offered by Stripe, Braintree, or most any low volume MOTO merchant account.
I don't think anyone can recommend what the best input method is without any knowledge of what your app is or who your customers will be.