Zap Request (Kind 5520)

To initiate a payment across the open network, a client generates a Kind 5520 (Zap Request) event.

This extends the standard NIP-57 ↗ Zap Request (Kind 9734 ↗) with two key changes that motivated new event kinds:

1. The p tag allows targeting legacy identities by accepting a ConnectionKey instead of strictly requiring a Nostr pubkey. The 3rd parameter denotes the provider (e.g., discord). If the 3rd parameter is empty or omitted, it defaults safely back to a native nostr pubkey.
2. Settlement is coin-agnostic, supporting any energy-backed asset routable over the Lightning Network — not limited to Bitcoin.

Event Structure

A Zap Request is created and signed by the sender's client.

{
  "kind": 5520,
  "content": "Here is 1000 loki! Great post.",
  "tags": [
    ["e", "<optional_target_event_id>"],
    ["a", "<optional_kind:pubkey:d_tag>"],
    ["k", "<optional_target_event_kind>"],
    ["p", "<recipient_pubkey_or_ConnectionKey>", "<optional_lidp_name>"],
    ["amount", "1000000"],
    ["chain", "flokicoin"],
    ["lnurl", "lnurl1..."],
    ["relays", "wss://relay.ohstr.com", "wss://nos.lol"]
  ],
  "pubkey": "<sender_pubkey>",
  "created_at": "<unix_timestamp>",
  "id": "...",
  "sig": "..."
}

Required Tags

Tag	Format	Description
p	["p", "<hex_or_ConnectionKey>", "<optional_lidp_name>"]	The target of the Zap. Can be a native Nostr 64-character hex key or a ConnectionKey. The 3rd element denotes the provider (e.g., discord). If omitted or empty, it defaults to nostr (pubkey).
relays	["relays", "<url1>", "<url2>"]	An array of relay URLs where the provider should publish the resulting Zap Receipt.
amount	["amount", "<milli-units>"]	The requested payment amount in milli-units (e.g., mloki, msats).
chain	["chain", "<string>"]	The network context, e.g., flokicoin or bitcoin.
lnurl	["lnurl", "<string>"]	The encoded LNURL the sender is requesting an invoice from.

Optional Tags

Tag	Format	Description
e	["e", "<hex>"]	Used if the Zap is in response to a specific Nostr event (e.g., tipping a specific note).
a	["a", "<kind>:<pubkey>:<d_tag>"]	Used if the Zap is in response to a parameterized replaceable event (e.g., tipping an article or badge).
k	["k", "<kind_number>"]	The stringified kind of the target event being zapped (e.g., "1", "30023").

Validation Rules

When a service or LN provider receives a Kind 5520 via an LNURL callback, it must strictly validate:

1. Signature: The event signature must be mathematically valid for the pubkey.
2. Amount: The amount tag must match the amount query parameter sent in the HTTP request.
3. LNURL: The lnurl tag must match the target being requested.
4. Chain Gating: The requested chain tag must match the provider's allowed routing chains.

If these conditions are met, the provider generates a Lightning invoice with the hash of this encoded JSON event embedded in the invoice's description hash (per LUD-11).