Paychex is a full-fledged digital payroll service that is widely used for businesses of all types and sizes to manage payroll processing and tax obligations. Related: 10 Questions to Ask When Choosing a Payroll Service What is Paychex? Explore the Paychex payroll service, including functions, features, integrations, customer support, and pros and cons. One of the most popular online, automated payroll service providers is Paychex. Many businesses today need payroll services, rather than in-house payroll, to run efficiently.