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Zbay – a private inbox, wallet, and marketplace all in one
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Zbay – a private inbox, wallet, and marketplace all in one

An online space controlled by the people of the Internet

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You can buy and sell things on Zbay, privately, with Zcash.
Collaboration timeframe:

January 2019 – ongoing

Team size:

2 software developers


Zcash, Node.js,React,Redux, Storybook, Docker, AWS


Research, App design, Back-end and Front-end development, Client support

About the client

Zbay’s founder is Holmes Wilson, an Internet freedom activist who was previously the co-founder and co-director of Fight for the Future, an organization devoted to campaigning for freedom and privacy online. He saw a need for an online platform for discussion and commerce that was based in free software and not dependent on centralized infrastructure. 

About the project

Zbay is an innovative desktop app that lets users create group discussions, send each other messages and money, and exchange goods. Currently, in the beta stage of development, the open-source app is free and available for Mac, Windows, and Linux. 

Instead of using a centralized system, Zbay is built on Zcash, a privacy-focused cryptocurrency. This means it can provide its users with a degree of privacy and autonomy unavailable in typical centralized platforms. Zbay uses the shielded transaction and encrypted memo functionality of Zcash to build a familiar user experience. Users can register a username, send messages, post items for sale, and purchase items—all using the Zcash network.

Zcash is an open-source digital currency based on Bitcoin, that is designed to provide privacy using zero-knowledge cryptography. Since Zcash lets you send private messages and protects metadata, it was an obvious starting point for building Zbay. 


Our client’s goal was to create a free and open-source desktop app that would function like a private inbox for messaging, transactions, and buying things. Instead of relying on a central server, the app would be built on the existing Zcash network, offering users the confidentiality lacking in popular existing platforms. The client’s objective was to create an online space that did not compromise on privacy and freedom, and in exchange offered users full control of their accounts. 

zBay buying with zCash screen shot
sending messages with zCash on zBay


Rumble Fish’s team architected, designed and developed Zbay – an innovative desktop app built on the Zcash network. 

Anyone can register a secure username or channel which gets engraved in the Zcash blockchain and has its own cryptographic key. Users can message each other, join group chats, buy and sell items, all without a centralized system. Zbay does not control who has an account or what is done with that account. Messages are encrypted in both private and public group chats, and senders and recipients of transactions are shielded from third party viewing.


Our team of developers built the app from scratch using basic tools provided by the Zcash project. As part of this work, our team contributed code that was merged into the open source Zcash project, and collaborated with Zcash developers to solve specific problems.

The application is written in Node.js, using React, Redux, and Electron. While working on the project, our team had to add some functions to Zcash itself. These changes had previously been planned, but not implemented, and were necessary for the app to work effectively.

The Zbay desktop app is Electron-based, which means the user interface is built using standard web technologies. The app uses the Zcash blockchain, so it must be launched locally on a user’s desktop, since it contains the user’s private keys and sensitive data.

Zbay is possibly the most advanced Zcash wallet currently on the market, with a clean UI and first-class support for encrypted memos. 

Zbay is an open-source project, funded in part by a grant from the Zcash Foundation.


  • Development of an innovative open-source desktop app based on Zcash

  • Continued improvement of the app

  • Successful long-term cooperation

Holmes Wilson picture

Rumble Fish has been really good at challenging assumptions or design decisions, to figure out the best path for the product. They’re not executing blindly towards some deliverable. They’re taking responsibility for making the best decisions as the work unfolds. I collaborated with them as a part of the team, and we built mutual trust and shared experiences along the way

Holmes Wilson

Founder of Zbay


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