The online payment startup associated with Max Levchin, Peter Thiel, and Elon Musk is PayPal.
The company’s early history is more complicated than the short founder list suggests. Levchin, Thiel, and Luke Nosek established Fieldlink in 1998; it became Confinity and developed a digital-wallet and money-transfer product called PayPal. In 2000, Confinity merged with X.com, the online financial-services company co-founded by Elon Musk.
After the merger, the payment product became the core business. The combined company adopted the PayPal name in 2001, went public in 2002, and was acquired by eBay later that year for about $1.5 billion. Musk therefore entered the PayPal story through X.com and the merger, while Levchin and Thiel were central to Confinity’s founding.
That corporate history explains why different sources list somewhat different PayPal founders, including Luke Nosek and other early contributors. Nevertheless, PayPal is the single canonical answer to this quiz question; Venmo, Square, and Stripe are separate payment companies.