Visa is the largest payment processor in the world. In fiscal 2018, it processed $8.2 trillion in purchase transactions. Visa operates in over 200 countries and processes transactions in over 160 currencies. Its systems are capable of processing over 65,000 transactions per second.

Mastercard is the second- largest payment processor in the world and processed $4.3 trillion in purchase transactions in 2018. Mastercard operates in over 200 countries and processes transactions in over 150 currencies.

PayPal was spun off from eBay in 2015 and provides electronic payment solutions to merchants and consumers, with a focus on online transactions. The company had 267 million active accounts at the end of 2018, including 22 million merchant accounts. The company also owns Xoom, an international money transfer business, and Venmo, a person-to-person payment platform.

American Express is a global financial institution, operating in about 130 countries, that provides consumers and businesses charge and credit card payment products. The company operates a highly profitable merchant payment network. Since 2018, the company has operated in three segments: global consumer services, global commercial services, and global merchant and network services. In addition to payment products, the company's commercial business offers expense management tools, consulting services, and business loans.