Bull Bitcoin, the longest‑running Bitcoin‑only exchange founded by Francis Pouliot, announced a deep integration of the Payjoin privacy protocol across its platform. According to a press release shared with Bitcoin Magazine, the exchange will now support Payjoin for deposits, withdrawals and on‑chain trading, making it the first exchange worldwide to offer these capabilities by default.

BTC / USD
Source: CoinGecko. Prices are indicative.

What is Payjoin and how it works

Payjoin is an on‑chain privacy protocol that disrupts traditional assumptions used by blockchain analysis firms, such as the expectation that one output of a transaction is change returned to the sender. By adding an off‑chain coordination layer, Payjoin mixes the amounts sent and returned, obscuring user intent without requiring a Bitcoin consensus change. The protocol relies on adoption by wallets and exchanges, and Bull Bitcoin’s implementation builds on work from the Payjoin Foundation.

Payjoin‑by‑default and automatic UTXO merging

When a BULL Wallet user buys or sells Bitcoin through Bull Bitcoin’s exchange, the transaction is automatically executed as a Payjoin. This automation aggregates a user’s UTXOs, a process the press release describes as “merging” coins to reduce future mining fees. By regularly consolidating UTXOs, the feature also helps shrink Bitcoin’s overall UTXO set, easing node operation and lowering fee pressure for the network as a whole.

Privacy benefits for traders

Because every trade on Bull Bitcoin is non‑custodial and leaves an on‑chain trace, traditional chain analysis can infer sensitive data such as salary or trading strategy. Payjoin trading, however, reduces the reliability of common heuristics that detect input ownership and change outputs, making it harder for third parties to deduce transaction values or patterns. The exchange claims that wider adoption of Payjoin will improve privacy for all Bitcoin users.

What to watch next

The rollout is tied to the open‑source BULL Wallet, which already integrated Payjoin V2 in December 2024. Observers will monitor how quickly users adopt the new defaults, whether other exchanges follow suit, and how the broader Bitcoin ecosystem responds to the potential reduction in UTXO set size and fee pressure.