What is PayJoin in Bitcoin?

PayJoin is a way of making a Bitcoin payment in which the person being paid also adds one of their own coins to the transaction. Because inputs come from both sides, someone watching the blockchain can no longer safely assume every input belongs to the sender. It is also known as Pay-to-EndPoint (P2EP), and earlier versions were called Bustapay.

How does PayJoin work in Bitcoin?

Bitcoin transactions spend coins, called UTXOs, as inputs and create new outputs. Chain analysis firms often apply the common-input-ownership heuristic, which treats all inputs in one transaction as owned by the same person. The BIP 77 authors note that even the Bitcoin white paper flagged this leak.

In a PayJoin, the sender builds and signs a normal payment as a PSBT and passes it to the receiver. The receiver adds one of its own inputs, increases its own output by the same amount, signs its part and sends it back. The sender checks that its inputs, outputs and fee rules have not been tampered with, signs, and broadcasts. On-chain, the transaction looks like a regular payment, but the real amount paid is hidden and the ownership guess is wrong.

What is PayJoin BIP 78?

BIP 78, written by Nicolas Dorier and now marked as deployed, is the first widely used PayJoin standard. The receiver shares a standard Bitcoin payment link that includes a "pj=" endpoint, and the two wallets exchange the transaction over that web address. The spec lists side benefits, such as letting the receiver consolidate coins or batch payments inside the same transaction.

The catch is that the receiver must run a secure public web server and be online at the moment of payment. That is easy for merchants using software like BTCPay Server but hard for someone with a phone wallet.

What is PayJoin v2?

PayJoin v2 is defined in BIP 77, drafted by Dan Gould and Yuval Kogman. It removes the need for a receiver server. Instead, both wallets leave encrypted messages in mailboxes on an untrusted directory server, so sender and receiver do not have to be online at the same time. Requests go through Oblivious HTTP so the directory cannot link them to IP addresses. It is designed to stay compatible with BIP 78 senders. Bitcoin Optech reports that BIP 77 was merged into the BIPs repository in 2025.

Which PayJoin wallets exist?

As of November 2026, Bitcoin Optech lists PayJoin support in software including BTCPay Server, Sparrow, BlueWallet, Wasabi, JoinMarket, Coldcard, Cake Wallet and Bull Bitcoin, plus a PayJoin client for Bitcoin Core and the Payjoin Dev Kit for developers. Support differs between v1 and v2, and between sending and receiving.

Cake Wallet's documentation shows the practical limits. The privacy benefit only applies if both wallets support PayJoin, the receiver needs some bitcoin in its wallet to contribute an input, and if the exchange of messages fails the payment falls back to a normal transaction. Unlike CoinJoin, PayJoin needs no coordinator or extra participants, and payjoin.org also promotes it as a way to save on fees by combining transactions.