I’ve asked around and got some information about recept validation:
- https://github.com/coilhq/receipt-verifier (Recommended)
- https://github.com/sabinebertram/ilp-torrent/tree/main/src/verifier-service
- https://wilsonianb.github.io/diagrams/receipts
“The receipt is an optional field in the monetizationprogress event. Receipts will only be present if a receipt verifier’s payment pointer is used. The web monetization sequence diagram shows how a receipt verifier fits into the flow.”