LNURL Server
The LNURL server is the payment side of AltZap. It is the same role NIP-57 ↗ calls the "lnurl server" (LNURL's "LN SERVICE"): the server behind a Lightning address that turns a zap request into an invoice and publishes the receipt. Zapf runs one.
Where an Identity Authority (IA) verifies who someone is, the LNURL server moves the money.
What it does
1. Issues the invoice
When you zap someone — on Nostr, Discord or X — your wallet sends a signed AltZap request to the recipient's LNURL server, which answers with a Lightning invoice bound to that exact request.
2. Settles the payment
Once you pay, the LNURL server forwards the value to the recipient's own wallet, for example over Nostr Wallet Connect (NWC).
3. Publishes the receipt
It then publishes a signed receipt (kind 9521) to Nostr. Clients check the receipt against the invoice and the original request, and show the zap.
4. Holds funds until they're claimed
If the recipient has no wallet yet, the LNURL server holds the payment at a Fallback Address until they sign in and connect one, then sweeps it to them.
Open to anyone
Anyone with Lightning liquidity can run an LNURL server, and users choose which one they trust.