Bull Bitcoin Turns Payjoin On by Default, and the Fee Savings Are the Real Story

Bull Bitcoin says it's the first exchange in the world to offer Payjoin as a deposit and withdrawal option. The Canadian company, founded by Francis Pouliot in 2013 and self-funded ever since, shipped two features at once. Payjoin-by-default routes every onchain buy or sell through BULL Wallet as a Payjoin. Payjoin trading is the second piece, where the amounts sent and returned get coordinated off-chain so the public record doesn't spell out what you're doing.

The fee math is the part people will scroll past, and it's the part that matters. Bitcoin users are supposed to periodically merge small UTXOs by spending them to a fresh address. Almost nobody does. Every unmerged dust output becomes a heavier input later, and inputs are what you actually pay for at confirmation time. Payjoin-by-default automates that merge during trades you were already making. Do it passively for a few years and your future fee bill shrinks. It also trims the global UTXO set, which lowers the hardware bar for running a node. That's infrastructure, and infrastructure is where the real costs hide.

Privacy is the headline. The change-output assumption and the common-input heuristic are the two load-bearing guesses behind most chain analysis, and Payjoin bends both. Because Bull Bitcoin is non-custodial and serves Canada, Europe, and Latin America, every trade it settles leaves a public trail. That's exactly why an exchange is a useful place to break those guesses. The code is open source and needs no soft fork or hard fork. December 2024 was the proof of concept, when BULL Wallet shipped the first Payjoin V2 integration with Dan Gould's team, the group that later formed the Payjoin Foundation.

Here's the take. Privacy that requires users to opt in doesn't scale, and defaults are the only thing that has ever moved onchain behavior. If rival exchanges don't copy this within a year, Payjoin stays a rounding error in global volume. Follow the hashrate, but watch the default settings too.