The Cashu team builds free and open-source, production-grade software that is beautiful, polished, and easy to use. We refuse to compromise between privacy and user experience. Privacy is a human right. Cashu is the world's largest Chaumian ecash ecosystem, built for Bitcoin and other currencies. People have sent money with Cashu through images, sound, satellites, radio waves, and more. It's incredibly fun. At the same time, we're pushing the frontier of digital cash research and development. We've built and explored: - Programmable ecash, combining Bitcoin-like spending conditions with ecash for scripting, multisig, HTLCs, and more - Open-source, phone-to-phone tap-to-pay - Unruggable ecash using TEE enclaves - Zero-knowledge credential ecash with blinded amounts and stronger privacy, using WabiSabi-style anonymous credentials - A migration from secp256k1 elliptic-curve cryptography to BLS pairing-based cryptography - A proof-of-liabilities scheme for ecash, optimized with sparse Merkle-sum trees for the ecash nullifier set - Multi-nut Lightning payments, aggregating a single payment across multiple Bitcoin Lightning nodes - Zero-knowledge scripts using STARK proofs and Cairo, contributed by StarkWare, enabling programmable ecash with spending conditions hidden even from the mint Every day, we're working to build digital cash for the next generation. That means crafting beautifully simple apps, equipping sovereign infrastructure, and pushing the frontier of cryptography. Always free. Always open source. Join us.