what it is
Fedi is an app built on Fedimint: federated Chaumian ecash. A group of independent operators - guardians - hold bitcoin together in a threshold multisig and issue ecash notes against it. The notes are blind-signed, so the guardians cannot see who holds what or who paid whom. Even the people running the mint can't build a profile on you. You join a federation, load it over Lightning, and from that moment your spending works like cash: no ledger entry with your name on it, nothing to hand over. Fully open source since January 3rd, 2026. Yes, they picked that date on purpose.
why it matters
Bitcoin's base layer is transparent - every node can verify everything, and that's what makes it honest money. It also means everyone can see everything. So privacy gets built on top, in layers: settlement at the bottom, Lightning for speed, ecash at the edges where you actually spend. Chaumian ecash is the original cypherpunk idea of digital cash - designed before bitcoin existed, and it died back then because there was no honest money underneath it. Now there is. Money that can be tracked is money that can be controlled. Inside a federation there is simply nothing to track.
how it holds up in the field
I'm testing a federation now - loading it, spending from it, using it day to day. I'll write this section when I have something real to say.
what you're trusting
Your ecash is backed by bitcoin the guardians hold together. No single guardian can freeze your money, censor you, or run off with it - one of them disappearing changes nothing, and that is the point of the design. But it's not your keys. If enough guardians colluded, the bitcoin behind the notes could move. Good federations spread guardians across people and places so they can't easily find each other, let alone conspire. Trust-minimized is the honest word - not trustless. My rule: spending money in the federation, savings in cold storage.
worth knowing
Fedi also ships encrypted chat and "mini apps" - small tools that run inside the app. Two of them are already in this directory: PlebQR and NadaNada. Scan a Thai QR, top up an esim, all from one place. I use them and they work. But they're a bonus, not the reason Fedi is listed here.
verdict
I'm testing the federation with real sats in the real world. Keep spending money in it, not savings. Full verdict when I'm done.