I decided to play with cashu so I made

https://paywally.pages.dev

It’s a standalone web app, no KYC, that implements a lightning paywall: you need to pay 21 sats to unlock the hidden content.

How it works:

• The app fetches a 19 sats invoice from bordalix@coinos.io
• Then it creates a melt quote with this invoice
• In return the app gets amount = 19 and fee_reserve = 2 sats
• It then creates a mint quote of 21 sats (19 + 2)
• In return the app gets a payment request (aka ln invoice)
• It shows this invoice to the user in qrcode and text
• It pools the mint every 5 seconds waiting for the invoice to be paid
• When paid, it mints the proofs
• Use these proofs to pay for the original invoice
• Receives a change of 2 sats and sends it to me via Nostr

It’s not perfect, the reader can sheat by inspecting the code and:

• Change the value to pay to 3 sats
• Change bordalix@coinos.io to his own lnurl
• Access the content in the code (is obfuscated, but is there)

Try it to get access to the code repo.