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Bitcoin developer Ben Allen has secured a $100,000 grant from Maelstrom, an investment firm, to advance the development of Payjoin. This privacy-enhancing tool aims to bolster Bitcoin’s scalability and privacy features. The grant, announced in May 2025, will fund Allen’s work on the Payjoin developer kit alongside Dan Gould.
Payjoin, initially proposed in 2019 as BIP 78 by Nicolas Dorier, allows both senders and receivers to contribute inputs to a transaction. This approach enhances privacy and improves the consolidation of transaction outputs, benefiting scalability. Maelstrom’s grant will be disbursed monthly over a year, totaling $100,000 in Bitcoin. The funding approach is hands-off, prioritizing the grantee’s autonomy.
Allen’s focus is on improving Payjoin implementations to facilitate its integration into more wallets. The grant allows him to dedicate himself full-time to the project. While Payjoin presents challenges—requiring the receiver to be online and involving more complex communication than typical Bitcoin transactions—its potential benefits are significant.
Arthur Hayes, Maelstrom’s CIO and former BitMEX CEO, emphasizes the importance of improving Bitcoin’s financial privacy. He highlights that even limited Payjoin adoption undermines a key assumption of financial surveillance companies: that multiple inputs in a transaction belong to a single entity. Maelstrom actively seeks to support further projects in the Bitcoin privacy space.
A crucial aspect of Payjoin’s success is its adoption by popular open-source Bitcoin wallets; integration into the Bitcoin Core wallet would be a major milestone. Ben Allen’s work involves creating benchmarks for developers to implement Payjoin in individual wallet software, alongside expanding test coverage for code consistency. He believes simplifying the user experience is vital for encouraging wider adoption. The benefits extend beyond direct users; Payjoin adoption improves privacy even for those who don’t actively utilize the feature.
