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AltZap Request (Kind 9520)

A kind 9520 AltZap Request is what a wallet signs to zap someone. It plays the role of NIP-57 ↗'s zap request (kind 9734), with two differences:

  1. The p tag can name a ConnectionKey instead of a Nostr pubkey, so you can zap a Discord or X account that has no Nostr key yet. Its third element names the platform (e.g. discord); empty means a Nostr pubkey.
  2. A mandatory chain tag says which Lightning-routable network the zap settles on, so a request can't be paid on another chain.

The full definition — tags, rules and the verification algorithm — is in NIP-AZ.

Example​

{
  "kind": 9520,
  "content": "Here is 1000 loki! Great post.",
  "tags": [
    ["p", "<recipient_pubkey_or_ConnectionKey>", "<optional_platform>"],
    ["amount", "1000000"],
    ["chain", "flokicoin"],
    ["lnurl", "lnurl1..."],
    ["relays", "wss://relay.ohstr.com", "wss://relay.primal.net"],
    ["e", "<optional_target_event_id>"]
  ],
  "pubkey": "<sender_pubkey>",
  "created_at": 1709424000,
  "id": "...",
  "sig": "..."
}

The signer is the sender, so a 9520 has no P tag. To zap on someone else's behalf, use an On-Behalf AltZap Request (kind 9523).

How Zapf handles it​

The wallet sends the request to Zapf's LNURL callback. Zapf's LNURL server checks the signature first, then that p is the address being paid, that amount matches the callback amount, and that chain is flokicoin. It then issues an invoice whose description hash is the SHA-256 of the request exactly as received.