Cashu is an open protocol for issuing and moving ecash denominated in sats. Its public specification is organised as NUTs, short for Notation, Usage, and Terminology. Wallet and mint implementations that follow the required NUTs can communicate without sharing one codebase.
A Cashu mint accepts Bitcoin through Lightning and issues bearer tokens to a wallet. Blind signatures let the mint sign a token without seeing the final token that the wallet stores. A user can pass the token as text, a QR code or another data message. The recipient can then swap it at the mint for fresh tokens or redeem it through the mint's supported payment path.
The privacy mechanism is narrow. It separates token issuance from later redemption, so the mint cannot directly connect those two events from the token itself. The project's own documentation also lists the limits. A mint can observe network metadata, Lightning payments in and out create privacy chokepoints, and rare token amounts can make activity easier to link.
Cashu does not remove custody risk. The mint holds the underlying bitcoin, and a token is a claim on that mint. The wallet stores bearer data on the user's device, so losing that data can also mean losing the funds. Users therefore rely on both the mint's ability to redeem and their own backup practices.
The project remains active. Its specification repository was updated on 28 September 2026, and the Nutshell reference wallet and mint released version 0.21.0 on 16 September 2026. The official site states that Cashu has no company, token or treasury. Its structure is therefore recorded as unincorporated, and no individual profile is needed for this entry. No official logo is copied; the directory uses its existing monogram fallback.