Here is a quick comparison of the credit card processing rates charged by the top payment processing services.CompanyPricing ModelProcessing Rates Square Flat rate 2.6% + $0.10 (retail)2.9% + $0.30 (online) Stripe Flat rate 2.7% + $0.05 (retail)2.9% + $0.30 (online) PayPal Flat rate ...