PayJoin v2 (BIP77)

[MatheyBTC]

This is a feature request to implement native PayJoin v2 (BIP77) support in Sparrow Wallet.

Bull Bitcoin Wallet has now shipped BIP77 in production for end users on mobile (Android/iOS). They built on top of the rust-payjoin library from the Payjoin Dev Kit, which provides a stable, battle-tested v2 implementation.

This means the hard work is done. The library exists, it works in production, and the protocol is mature.

Payjoin v2 eliminates the main friction of v1:

• No server required — the receiver uses an untrusted Payjoin Directory instead
• Async — sender and receiver don't need to be online simultaneously
• Private — communication is encrypted end-to-end via Oblivious HTTP (OHTTP)
• Compatible — extends the existing BIP21 URI format

Sparrow's users are exactly the audience that would benefit most: desktop users who want strong privacy but don't run dedicated infrastructure. Adding BIP77 would make Sparrow the first desktop wallet with native Payjoin v2 support.

References

• BIP77 spec: https://github.com/bitcoin/bips/blob/master/bip-0077.mediawiki
• rust-payjoin library: https://github.com/payjoin/rust-payjoin
• Receiver tutorial (Payjoin Dev Kit): https://payjoin.org/docs/tutorials/receive-payjoin-v2/
• Bull Bitcoin announcement: https://www.bullbitcoin.com/blog/bull-bitcoin-wallet-payjoin
• Related: Sparrow won't sign a PSBT input by OutPoint if TXO details are missing #1428 (Dan Gould's v2 test attempt with Sparrow)

Happy to help test or provide feedback from a user education perspective.

[tartly8]

That would be awesome!