Fun is a New York-based payments infrastructure company that builds unified deposit, withdrawal, and settlement rails spanning fiat currencies and digital assets. Its API-first money layer powers high-volume consumer platforms including Polymarket, Lighter, and Aave, processing over $18 billion in annual transaction volume across more than 100 countries. Founded in 2022 by Stanford dropout Alex Fine, the company positions itself as a neutral bridge between banks, stablecoins, and onchain markets for fintechs adopting tokenized money.