Justin says Fedimint's eCash app is positioned as a reference client and now includes a Nostr-based contact system, allowing users to input any Nostr public key to populate payment contacts without logging in.
The eCash app uses Nostr for a non-custodial recovery mechanism. It encrypts and stores federation invite codes on relays, derivable solely from the user's seed phrase.
Fedimint is a chaumian eCash system using a federation of guardians. It employs a multisig where, in a typical four-guardian deployment, three signatures are required to move funds.
Justin argues the primary operational risk for eCash systems like Fedimint is unintentional uptime failure, not malicious rug pulls, because running high-availability services is difficult for average operators.
Fedimint now offers Start9 and Umbrel packages for easy guardian deployment. The setup involves a ceremony where guardians exchange codes, now facilitated by QR codes for in-person setup.
The project uses Iroh for peer-to-peer networking, removing the previous DNS requirement. Clients and guardians communicate directly via Iroh, which supports hole punching and relayed modes.
Justin states running a guardian can expose your IP to users and your ISP. He recommends using a VPN like Mullvad for privacy, as integrated Tor support is still in development.
Fedimint's Lightning Gateway is a separate entity that facilitates payments. Users trust it for uptime and liquidity, not custody, as funds remain secured by the federation's multisig.
A gateway can serve multiple federations, enabling capital efficiency. If a payment occurs between two users on federations served by the same gateway, it becomes an internal ledger transfer, not a Lightning payment.
Justin's team released an Android app that can run a Fedimint guardian, drastically lowering the barrier to entry. It runs as a foreground service, is data/power intensive, and allows setup via QR codes.
The Android guardian app can use Explora (Mempool.space) by default for blockchain data but can also be configured to connect to a local Bitcoin Core node.
Justin sees eCash as well-suited for AI agents because it outsources Lightning complexity. Using a personal mint for an agent provides a potential 'undo button' if the agent loses its wallet database.
Odell notes a community in South Africa is using Fedimint as a daily driver for expenses, indicating early adoption for local community banking use cases.
Justin says upcoming work includes making the gateway more agent-friendly, adding new consensus modules, and implementing Bolt 12, though Bolt 12 presents a trust model challenge similar to LNURL.