Calle launches BitNotes, a multi-mint Cashu wallet that prints ecash on paper

Bitcoin has spent years trying to act like cash. A pseudonymous developer has now taken that idea literally.

Calle, the developer behind the Cashu ecash protocol, announced BitNotes on October 22, 2026. It is a free, open-source, multi-mint Cashu wallet that lets users print ecash as physical paper notes. Those notes can be verified offline before anyone tries to redeem them.

What BitNotes actually does

At its core, BitNotes is a wallet for Cashu, an ecash system built around Bitcoin. Ecash tokens are issued by entities called mints. Users hold those tokens and pass them around much like digital bearer instruments.

The headline feature is printing. BitNotes can generate paper notes that represent ecash tokens. Verification happens offline using the mint’s public keys. The recipient can check a note against the issuing mint’s cryptographic signature without a network connection. Redemption comes later, once the holder is ready to turn the note back into digital ecash.

The notes are also designed to be tamper-evident. If someone has messed with a note, the holder should be able to tell.

The app handles standard digital ecash transfers too. It integrates with Lightning, Bitcoin’s layer for fast payments, so users can move value in and out of the ecash system.

For getting on-chain Bitcoin into the wallet, BitNotes uses Ark. It also offers support for Mobile Money systems, including a bridge for Rwandan Francs.

Why multi-mint matters

The “multi-mint” label is doing real work here. In Cashu, a mint is the party that issues and redeems ecash. BitNotes is built to spread that risk across several independent mints, such as 28MINT. Users can route transactions through different mints. The app can also 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.

The Cashu backstory

BitNotes did not appear from nowhere. Calle has been developing Cashu since the protocol was open-sourced in October 2022.

So far, the rollout appears to be 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 points toward users in regions where banking infrastructure is thin. Offline verification, physical notes and a Mobile Money bridge for Rwandan Francs all target people who may not have reliable connectivity or bank accounts.

Paper ecash introduces familiar cash problems: notes can be lost, damaged or stolen. Tamper-evidence helps, but it does not make a note fireproof.

Ecash depends on mints, and users ultimately need to believe the mints behind their notes will honor redemptions. The multi-mint design reduces dependence on any single operator, but it 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.

The things to watch are straightforward. Look for audit results, growth in the number of independent mints, expansion beyond Android and macOS, and any real-world usage of the Mobile Money bridge.