Coinbase

Founded in 2012 by Brian Armstrong, formerly of Airbnb, and Fred Ehrsam, a Goldman Sachs trader, it went through Y Combinator that summer. The pitch was about friction rather than technology: instead of hunting for sellers on forums, you linked a bank account and bought. Coinbase also holds the keys on the customer's behalf – convenient, and precisely the kind of intermediary bitcoin was designed to make unnecessary.

Its direct listing on Nasdaq in April 2021 landed almost to the day on bitcoin's then all-time high. Since then it has bought cryptographers (Yehuda Lindell's Unbound Security), launched its own Ethereum layer-2 network, Base, and spent a good part of the 2020s in court with US regulators.