This app is what my wife currently uses for her photography business and I will follow suit for my hydrodipping. They send you a free card reader that plugs into the headphone jack on your smartphone. You need to be connected to the internet to use it, wifi or mobile data. It will charge you 2.7% of the transaction for swiping the card. Recently we just started using the invoicing feature which costs 2.9% of transaction + $0.30. While these fees seemed high at first, we have a low amount of swipes per month which made typical merchant services undesirable because of a monthly fee. PayPal has no monthly fee. Also, I have a business debit card (Mastercard) that is attached the account directly. So as soon you get paid, you could turn around and use the card right away with your available funds.
This apps biggest competitor is Square but I already had the PayPal account and the added debit card feature is nice with no turnaround time to use your money.
If anybody has any questions, we are avid users of the app and could probably answer them.