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@ kukks
2025-03-31 07:44:15
With all the current hype around Payjoin for the month, I'm open-sourcing a project I developed five years ago: [https://github.com/Kukks/PrivatePond](Private Pond)
Note: this project is unmaintained and should only be used as inspiration.
Private Pond is a Bitcoin Payjoin application I built specifically to optimize Bitcoin transaction rails for services, such as deposits, withdrawals, and automated wallet rebalancing.
The core concept is straightforward: withdrawals requested by users are queued and processed at fixed intervals, enabling traditional, efficient **transaction batching**. Simultaneously, deposits from other users can automatically batch these withdrawals via **Payjoin batching**, reducing them onchain footprint further. Taking it to the next step: a user's deposit is able to fund the withdrawals with its own funds reducing the required operational liquidity in hot wallets through a process called the **Meta Payjoin**.
The application supports multiple wallets—hot, cold, multisig, or hybrid—with configurable rules, enabling automated internal fund management and seamless rebalancing based on operational needs such as min/max balance limits and wallet ratios (10% hot, 80% in 2-of-3, 10% in 1-of-2, etc) .
This system naturally leverages user Payjoin transactions as part of the automated rebalancing strategy, improving liquidity management by batching server operations with user interactions.
Private Pond remains quite possibly the most advanced Payjoin project today, though my [multi-party addendum of 2023](https://x.com/MrKukks/status/1690662070935564289) probably competes. That said, Payjoin adoption overall has been disappointing: the incentives heavily favor service operators who must in turn actively encourage user participation, limiting its appeal only for specialized usage. This is why my efforts refocused on systems like Wabisabi coinjoins, delivering not just great privacy but all the benefits of advanced Payjoin batching on a greater scale through **output compaction**.
Soon, I'll also open-source my prototype coinjoin protocol, **Kompaktor**, demonstrating significant scalability improvements, such as 50+ payments from different senders being compacted into a **single Bitcoin output**. And this is not even mentioning [Ark](https://arklabs.to), that pushes these concepts even further, giving insane scalability and asyncrhonous execution.
You can take a look at the slides I did around this here: https://miro.com/app/board/uXjVL-UqP4g=/
Parts of Private Pond, the pending transfers and multisig, will soon be integrated into nostr:npub155m2k8ml8sqn8w4dhh689vdv0t2twa8dgvkpnzfggxf4wfughjsq2cdcvg 's next major release—special thanks to nostr:npub1j8y6tcdfw3q3f3h794s6un0gyc5742s0k5h5s2yqj0r70cpklqeqjavrvg for continuing the work and getting it to the finish line.