Cashu is Ecash for Bitcoin

Cashu is a free and open-source Chaumian ecash system built for Bitcoin. Cashu offers near-perfect privacy for users of custodial Bitcoin applications. Nobody needs to knows who you are, how much funds you have, and with whom you transact.

What is Cashu?

Cashu is a new ecash protocol for custodial Bitcoin applications that is tightly integrated into the Lightning network. An Ecash system consists of two parts, the mint and the Ecash wallet. Ecash transactions between users are untraceable and instant. A Cashu mint does not know who you are, what your balance is, or who you're transacting with. Users of a mint can exchange ecash privately without anyone being able to know who the involved parties are. Bitcoin payments are executed without anyone able to censor specific users.

Features

Open-source Ecash

Cashu is a free and open-source protocol. Anyone can run a mint.

Bearer token

Ecash transactions are instant and final, just like physical cash.

Untraceable

Blind signatures preserve user privacy. Transactions are peer-to-peer.

Programmable

Cashu tokens support spending conditions like P2PK and HTLCs.

Ecash for the web

Ecash payments can be included in web requests.

Range of application

Use Cashu for your website. Or a whole bank.

Explore Cashu

Cryptography

Cashu is an Ecash implementation based on David Wagner's variant of Chaumian blinding.

Protocol

Cashu NUTs (Notation, Usage, and Terminology) are Cashu's protocol specifications and the developer libraries make it easy to write wallets and mints.

Apps

There are many apps that implement the Cashu protocol. Apps are available as mobile apps for iOS and Android, progressive web apps (PWA), and command-line tools (CLI).

Libraries

Cashu libraries are available for various programming languages. Click here to see the full list. Here are some examples.

Resources

Learn about Cashu

Articles and Podcast about Cashu and Chaumian ecash.

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Explore Projects

Explore the different Open Source Cashu apps that have been built so far.

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Cashu Protocol

Go deeper into how the Cashu protocol works.

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Join Cashu R&D

We have a Discord server and a Telegram channel focussed on Cashu R&D. If you're developer, please join us!