Service-based small businesses — barber shops, salons, food trucks — often run cash-only because card processing fees eat into already thin margins. Coin, my Harvard Business Analytics Program capstone, was a proposal to fix that. The platform had three components: C-Coin, a USD-pegged stablecoin; a private Ethereum-based settlement network; and Coin Pay, a mobile wallet that merchants could use to accept payments without specialized hardware. Together they aimed to bring low-cost card acceptance to minority-owned small businesses, starting in Harlem and other underserved New York City neighborhoods. The paper also covered machine-learning-based fraud detection, customer-privacy guarantees, and an international remittance roadmap. It was a research artifact rather than a shipping product, but the problem it addressed stuck with me.
Read the paper: Coin: Secure Mobile and Online Payments for Small and Medium Enterprises — Harvard Business Analytics Program submission (Ideation | Pitch).
Update: I'm now building this for real as a native iOS app — see CoinMobile: Rethinking Small Business Payments on iOS. The blockchain piece is gone (Stripe Connect handles settlement instead of a private chain), but the core thesis is the same: a 1% fee structure aimed squarely at the small-business segment that incumbent processors overcharge.