Fedimint
Also: federated mint
lightning · advanced
A federation of guardians runs a Chaumian e-cash mint backed by Bitcoin. Privacy and scalability for community-sized groups.
David Chaum's e-cash (1982) was the original digital cash: a server issues blind-signed tokens; users redeem them anonymously. The flaw was that the server could inflate or steal. Fedimint (Eric Sirion, 2022) replaces the single server with a federation — typically 5–15 trusted guardians using threshold cryptography. No single guardian can mint or steal; takes a quorum.
The user experience: deposit BTC into the federation; receive blinded e-cash tokens called fedimint notes; spend them privately within the federation; redeem back to BTC on Lightning. Transfers inside the mint are instant, private, and effectively free. The federation never sees who paid whom.
The tradeoffs are real. You're trusting the federation as a group not to collude. Best fit is community-scale — village savings groups, family banks, congregations — where members already trust each other. It's a different point in the design space from full self-custody, with very different UX and privacy properties.