Cashu Developers Are Working to Bring Payjoin Privacy to Bitcoin-Backed Ecash
During the weekly Cashu Development Kit contributor call held on June 17, 2026, at bitcoin++ Nairobi, developers discussed PR2049, a pull request that aims to integrate Payjoin into the Cashu implementation. As of the call, the PR remains in draft. In parallel, developers are working to draft a specific NUT, the protocol specification format used in Cashu, for Payjoin. The proposal builds on top of NUT-30, which introduced on-chain minting and melting into the Cashu protocol, and on BIP77, the proposal for the asynchronous version of Payjoin.
For context, Cashu is a Bitcoin-backed ecash protocol that allows anyone to run their own mint, enabling privacy-preserving instant payments. Transactions are settled through the Lightning Network, with blind signatures ensuring that the mint cannot link individual payments to individual users. The missing piece has been on-chain privacy: when a user deposits Bitcoin into a mint to receive ecash, that on-chain transaction can still be traced. Payjoin integration addresses exactly that gap.
What Payjoin Actually Does
Payjoin is a technique that allows two parties in a transaction to each contribute inputs, making it significantly harder for blockchain analysis companies to determine which inputs and outputs belong to which participant. By breaking the common input ownership heuristic that most chain surveillance tools rely on, Payjoin degrades the effectiveness of tracking tools at a protocol level rather than requiring individual users to take any special action.
The asynchronous version of Payjoin, formalised in BIP77, removes the earlier requirement that both the sender and recipient be online simultaneously during a transaction. An external directory handles the coordination without seeing the content of the messages, while OHTTP protects metadata. This makes Payjoin practical for a much wider range of use cases than the original synchronous version.
Why This Matters for Everyday Bitcoin Users
For users of Cashu wallets across Africa and globally, the practical implication is straightforward. When you deposit Bitcoin into a Cashu mint today, that deposit transaction is visible on-chain and can be linked to your subsequent ecash activity if an observer is watching. With Payjoin integrated into the minting process, that link becomes significantly harder to establish. Combined with Cashu’s existing blind signature privacy model, a Payjoin-aware Cashu mint would offer meaningful end-to-end privacy from deposit through to payment, without requiring the user to understand or configure anything.