Stripe

Stripe dominates the US payment landscape as the largest privately-held processor, handling $1T+ in total payment volume annually—a figure that outpaces Square's entire ecosystem. With $15B in revenue and a $65B+ valuation from its most recent funding round, it powers payments for over 1 million businesses, including Shopify and Amazon. Its infrastructure-first approach enables seamless online and in-person transactions, processing more than 50 million API requests daily. Despite remaining private, Stripe's scale and reliability make it the default choice for fast-growing companies, outperforming #6 Square in enterprise adoption and developer preference.