Stripe

Stripe is a comprehensive, API-driven platform for internet businesses. It excels with its powerful, well-documented APIs for payments, subscriptions, invoicing, and complex revenue models like marketplaces. Target audience is developers at tech companies and SaaS platforms. It operates on a pay-as-you-go model (2.9% + $0.30 per successful card charge).

It ranks first due to its unparalleled flexibility, extensive global reach (135+ currencies), continuous innovation (Stripe Connect, Elements), and robust suite of financial products including corporate cards and lending.