Cashu is a free and open-source Chaumian ecash system built for Bitcoin. Cashu offers near-perfect privacy for users of custodial Bitcoin applications. Nobody needs to knows who you are, how much funds you have, and with whom you transact with.
Open wallet Documentation View on GitHubCashu is built for Bitcoin. Wallets use the mint's Lightning node for making or receiving Bitcoin payments in exchange for ecash.
A Cashu mint does not know who you are, what your balance is, or who you're transacting with. Users of a mint can exchange ecash privately without anyone being able to know who the involved parties are. Bitcoin payments are executed without anyone able to censor specific users.
There are multiple implementations of the Cashu protocol. Cashu is available as a command line interface (CLI) tool and as Progressive Web Apps (PWA) with a graphical user interface. Check out the Nutstash wallet as an example.
Cashu NUTs (Notation, Usage, and Terminology) are the protocol specifications. Multiple Cashu client libaries make it easy for developers to write their own wallets.