BTCPay Server — Payjoin + scoring

BTCPay Server supports BIP-77 async Payjoin out of the box. When a customer pays a BTCPay invoice with a Payjoin-capable wallet, the transaction has a pj= parameter in the BIP-21 URI — which SiriScore detects as H11.

Scoring a BTCPay payment

When a BTCPay invoice is paid, you can score the PSBT before broadcasting by passing the full BIP-21 URI:

from siriscore import score_as

# BIP-21 URI from BTCPay invoice
payment_uri = "bitcoin:BC1QXXX...?amount=0.01&pj=https://btcpay.example.com/BTC/pj"

report = score_as(
    psbt_base64,
    input_type="psbt",
    psbt_meta={"payment_uri": payment_uri},
)

if report.score < 60:
    print("Warning: low privacy score before broadcast")

H11 and Payjoin

When the pj= endpoint is present, H11 fires as a positive (green) finding:

• Info — Payjoin endpoint available, consider using it
• Warning — escalates when H5 (high input count / CIOH) also fires, because Payjoin directly mitigates that risk

Webhook integration (coming)

A future version of SiriScore will support webhook callbacks so BTCPay can automatically score transactions and flag low-scoring payments for review.