Cashu Highlights Q3/25

Cashu is a Chaumian ecash protocol built for Bitcoin that enables instant and private Bitcoin payments. In this third quarterly report of the year, we're featuring ongoing developments including libraries and wallet updates, Orchard, a mint management system, developments in decentralized private access to AI, Bitchat, and insights into Cashu Design.

Libraries 

Cashu Development Kit (CDK)
Over the past quarter, multiple new versions of CDK have been released, including two major updates: v0.12.0 and v0.13.0.

Version v0.12.0 introduces several significant enhancements, most notably full end-to-end support for BOLT12 transactions and the addition of cdk-ldk-node, a Lightning backend that enables a single binary to operate both a Cashu mint and a Lightning node.

Version v0.13.0 delivers significant improvements for mobile development. It introduces native mobile bindings, allowing developers to build Cashu wallets in Swift for iOS and Kotlin for Android. This is made possible by the newly added cdk-ffi, a Foreign Function Interface (FFI) crate written in Rust, which allows Rust code to be called directly from Swift or Kotlin.

These updates make CDK a fundamental component of Cashu’s development paving the way for broader Cashu adoption.

coco
coco is a TypeScript library based on cashu-ts for developing Cashu wallets and applications. It provides a unified, platform-agnostic API that simplifies the development of Cashu wallets and their integration into various environments such as browsers, Node.js, and React Native.

coco comes with ‘batteries included’: it manages all wallet-specific state transitions for the implementor, and even comes with its own database. It has never been easier to build a Cashu wallet. Everyone can now build a wallet without diving deep into the Cashu protocol.

Wallets

eNuts
The first major adopter of coco is a renewed and streamlined version of the popular mobile wallet eNuts. The entire Cashu logic of eNuts is managed by coco, while the wallet's codebase focuses on the UI/UX. An alpha version of the new eNuts is expected to be released in the coming weeks.

macadamia 
macadamia, a native Cashu wallet for iOS, has released a new version introducing an iMessage extension that allows users to send Bitcoin via ecash directly through iMessage.

The release received significant attention and highlights the potential of the Cashu protocol to make Bitcoin transactions accessible to a wider audience. 

Mint management

Orchard
Orchard is a new web application for Cashu mint management that can run on your own server. It allows operators to manage their Cashu mint and also to control their Bitcoin and Lightning infrastructure (and soon Taproot Assets) all within the same interface. Orchard comes with an AI layer via a locally hosted LLM integration, enabling more efficient management and task automation.

Artificial Intelligence

CypherFlow
CypherFlow enables decentralized and privacy-preserving access to AI models using ecash and Nostr. Users pay per message through an integrated ecash wallet with Lightning support. CypherFlow uses Nostr private key identity for encrypted message backups. Chats are client side end-to-end encrypted, ensuring privacy without requiring any account or subscription.

CypherFlow makes it easy to access AI while protecting users’ privacy, thanks to Cashu.

Routstr Core
Routstr Core is a FastAPI reverse proxy that lets users pay for AI API requests with Cashu tokens. It validates tokens, deducts costs per request, and supports flexible pricing models.

OTRA
OTRA allows users to make anonymous microtransactions using ecash to access OpenAI APIs. A local proxy manages the Cashu notes, while a 402 server processes payments and redemptions.

Together, Routstr Core and OTRA demonstrate the integration of Cashu payments into AI services.

Zero-Knowledge Proofs and Cashu

Yofthahe Yeshitila and Vincent Palma from StarkWare have proposed a new NUT specification for the integration of Zero-Knowledge Proofs into the Cashu protocol, allowing users to set specific conditions for spending ecash. These conditions, called Cairo Spending Conditions, use STARK proofs to verify that transactions are valid without revealing the locking script to the mint. Zero-Knowledge Proofs can enhance Cashu's flexibility in token spending while maintaining privacy. 

Bitchat 

Internet connection. When connected to the Internet, it uses the Nostr protocol for global communication. Bitchat uses the Noise Protocol for encrypted messaging, enabling private and censorship-resistant communication. Bitchat is available for iOS, developed by Dorsey, and Android, developed by Calle.

The usefulness and necessity of Bitchat were proven recently during multiple global events. In Nepal, it was used by young people protesting the government after it blocked several social media services.

In Madagascar, Bitchat downloads spiked at the end of September in the context of ongoing protests against water and power shortages. Hurricane Melissa in Jamaica led to a noticeable increase in downloads, underlining Bitchat’s utility during natural disasters that disrupt internet access.

During the Cashu developer retreat this summer, a Cashu wallet was integrated into Bitchat, enabling sending ecash via Bluetooth without an internet connection. Though not officially integrated yet, the concept demonstrates the potential of open-source software to build a free internet through permissionless communication and payments.

Design

Vibe Designing
Design is an essential part of Cashu adoption by making Bitcoin more accessible and user-friendly. During the Cashu developer retreat, Cashu Designer Erik vibe designed a Bitchat Cashu wallet using Kotlin and CDK, leveraging Figma and Cursor MCP. This process shows that design and software development complement each other to improve usability and functionality.

New Cashu Brr Design
With Cashu Brr, users can print a physical paper note with a QR code that holds redeemable Cashu tokens. The note can be handed to someone like physical cash, allowing them to scan and redeem it immediately or if they’re offline, the token can  be stored and redeemed later.

Cashu Brr now shines in a new design: Check it out and print some notes! It’s fun, and great for introducing new people to Cashu

Overview

Q3 has been a period of steady progress across the Cashu ecosystem. Cashu libraries received major upgrades and have become more developer-friendly. Cashu's integration into iMessage, along with projects such as Orchard, CypherFlow, and Routstr, show its growing range of applications and versatility.

With its ongoing development, Cashu is becoming a crucial part of the Bitcoin ecosystem by enhancing privacy and usability in Bitcoin transactions, as well as providing developers with the tools they need to build on the Cashu protocol.