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Fast. Private.
Simple. Secure.

Electronic cash for payments online, in person, and around the world.

WHAT'S CASHU

Digital payments should be as natural as handing over cash in person. Cashu brings simplicity back to online payments.

Cashu is a free and open-source Chaumian ecash protocol built for Bitcoin. A digital bearer token that is stored on a user's device, very similar to physical cash. The Cashu protocol allows you to build applications such as wallets or voucher systems. Transactions are instant and nearly free.

Cashu is an ecash protocol that is integrated with the Bitcoin protocol. An ecash system consists of two parts, the mint and the wallet. Anyone can run a mint for their application, be it a wallet, a web paywall, paid streaming services, or a voucher and rewards system for a super market.

Ecash transactions between users or service providers respect the user's privacy. A mint does not store a database of user accounts and their activity which protects users from leaks or hacks and can provide stronger censorship resistance than classical payment systems.

FEATURES

Core functionalities that define Cashu's approach to secure, private transactions.

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.

Privacy focused

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

Ecash for the Web

Ecash payments can be included in web requests. Use Cashu for your website or application.

HOW IT WORKS

Users deposit bitcoin into their mint and receive ecash. For transfers between mints, payments are routed through the lightning network for fast, secure transfers. Users can redeem their ecash tokens for bitcoin at any time.

EXPLORE CASHU

Discover the building blocks of the Cashu ecosystem.

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 open source apps that have already implemented the Cashu protocol available as mobile apps for iOS and Android, progressive web apps (PWA), and command-line tools (CLI).

DISCOVER APPS

Libraries

Cashu is available and ready for implementation in various programming languages like Python, TypeScript, Rust and Golang.

Learn about Cashu

Articles and podcasts about Cashu and Chaumian ecash. Read more

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Alice's Payment

Enter amount

40,000sats

DEVELOPERS, DEVELOPERS, DEVELOPERS

The specifications, called Cashu NUTs (Notation, Usage, and Terminology) describe how to implement the protocol. Multiple Cashu client libaries make it easy for developers to write their own wallets in their favorite programming language.

SOURCE CODE

SUPPORT

Your support can ensure the sustainable development of free and open-source digital cash projects using the Cashu protocol. As digital cash becomes integral to future payment infrastructure and financial services, we need your help to keep these systems public and accessible to all.

SUPPORT OPENCASH ASSOCIATION

JOIN CASHU R&D

We have a Matrix space and a Telegram channel focused on Cashu R&D. If you're a developer, please join us!

Fast. Private.Simple. Secure.