Last month, on July 7th, news spread amongst Bitcoiners. Someone had finally added support for bitcoin payments to Signal, the open-source, end-to-end encrypted messaging app.
Well, not Signal exactly. Radar Chat, a newly launched fork of the open source Signal project, takes the private communication network of Signal and adds Bitcoin, p2p electronic cash.
One of the minds behind the integration is Cake Wallet’s COO, Seth for Privacy.
On X, he presented Radar Chat to the world, describing it as the best way to address one the biggest issues our digital life has: sending money and communicating should be our most private acts, but in reality this is where surveillance is strongest. Radar Chat aims to provide a unified tool for people to protect themselves from surveillance for both the movement of money and information.
Radar Chat’s launch is exciting, but it is not exactly novel. Someone had already created a proof of concept of a similar solution some months before Radar Chat finally saw the light of day, and launched a campaign to raise awareness on the fact that private messaging needs private money.
It All Started with an Hackathon
Back in October 2025, developers from all over Europe came together in Berlin, Germany to compete to win the Bitcoin++ — Lightning Edition Hackathon.
One team had a simple, but powerful idea. Not many people know about it, but Signal has a built-in cryptocurrency wallet which can be used to exchange money between users. It only supports MobileCoin, a shitcoin that not even its creator remembers exists. The team, composed of some of the most knowledgeable developers in the Cashu ecosystem, decided to swap that wallet with a Cashu one, using the UniFFI bindings for Swift and Kotlin available on the Cashu Development Kit.
The project, Nuts Are Pure Signal, won. At the hackathon finals, they demoed sending ecash tokens back and forth between an Android and an iOS device using their custom Signal client.
The Android fork is still available on GitHub.
Private Messaging Needs Private Money
Less than two weeks later, the Cashu team, with the help of the Bitcoin Design Community, launched a dedicated campaign to raise awareness on the fact that private communication and private money go hand-in-hand.
The campaign was well received, with prominent bitcoiners, such as Peter Todd and Jack Dorsey, vocally supporting the effort. Bitcoin Designer Erik Cativo discussed in a retrospective that one of the strong points of the campaign was its focus on the design, which helped “presenting the idea elegantly and professionally”. The X hashtag #bitcoinforsignal remains the proof of the impact of the campaign.
Closing the Loop
Seth did not forget to give credit to the campaign. On July 10th, he published the following tweet with the #bitcoinforsignal hashtag.
Radar Chat is not based on Cashu, but provides a Lightning wallet based on Spark. While the technology is different, the ethos remains the same.
Freedom of speech and freedom to transact belongs together.
What’s Next?
In his review of “A Lodging of Wayfaring Men”, Max Hillebrand chooses Bitcoin++ as one of the modern lodges in which the future is being built. “Bitcoin++ pulls protocol engineers into the same room to prototype and ship across a single shared agenda,” he says. Having hackathon projects inspire real products and real advancement in the ecosystem is one of the things we are more proud of.
Next Stop: Berlin
Bitcoin++ is coming back to Berlin next month, 1-3 October 2026. Join us, if you want to be part of the builders shaping the future of Bitcoin!