Calle, the developer behind the Cashu ecash protocol, announced BitNotes on October 22, 2026. BitNotes is a free, open-source, multi-mint Cashu wallet that allows users to print ecash as physical paper notes, which can be verified offline before redemption.
What BitNotes does
BitNotes is a wallet for Cashu, an ecash system built on Bitcoin. Ecash tokens are issued by entities called mints, and users hold and transfer them like digital bearer instruments. The key feature is printing: BitNotes generates paper notes representing ecash tokens. Verification happens offline using the mint’s public keys, so a recipient can check a note against the issuing mint’s cryptographic signature without a network connection. Redemption occurs later, when the holder converts the note back to digital ecash. The notes are also designed to be tamper-evident.
The app also handles standard digital ecash transfers and integrates with Lightning, Bitcoin’s layer for fast payments, to move value in and out of the ecash system. For on-chain Bitcoin, BitNotes uses Ark. It also supports Mobile Money systems, including a bridge for Rwandan Francs.
Why multi-mint matters
In Cashu, a mint issues and redeems ecash. BitNotes is built to spread risk across several independent mints, such as 28MINT. Users can route transactions through different mints, and the app can automate swaps between them to make payments more reliable.
Availability is currently limited to Android and macOS. The code is released under MIT and Apache licenses.
Cashu backstory
Calle has been developing Cashu since the protocol was open-sourced in October 2022. The rollout of BitNotes appears early-stage: coverage has largely been limited to Calle’s own announcement and activity within the Cashu community. No external security audits have been disclosed, and there are no concrete adoption figures yet.
What this means
The feature set targets users in regions with thin banking infrastructure. Offline verification, physical notes, and a Mobile Money bridge for Rwandan Francs all aim at people who may lack reliable connectivity or bank accounts.
Paper ecash introduces familiar cash problems: notes can be lost, damaged, or stolen. Tamper-evidence helps but does not make a note fireproof. Ecash depends on mints, and users must believe the mints behind their notes will honor redemptions. The multi-mint design reduces dependence on any single operator but does not remove the need for trust altogether.
Without a public audit, early users are effectively testing the software in the wild. Anyone printing meaningful amounts onto paper should probably start small.
Things to watch include audit results, growth in the number of independent mints, expansion beyond Android and macOS, and real-world usage of the Mobile Money bridge.
