content: Optional comment/message accompanying the zap
Kind 9734 is a zap request – a Lightning Network tip request event. The client creates a kind 9734 event targeting the recipient and sends it to the recipient's Lightning wallet server (LNURL-pay endpoint). The wallet generates a Lightning invoice and, upon payment, publishes a kind 9735 zap receipt to Nostr relays. Zaps are Bitcoin Lightning micropayments tied to Nostr events.
Details
Zaps (NIP-57) integrate Bitcoin Lightning Network payments into the Nostr social experience.
Flow: 1. Client creates kind 9734 (zap request) event targeting the recipient pubkey and optionally a specific event 2. Client fetches recipient's LNURL-pay endpoint from their lud16 (Lightning address) in kind 0 metadata 3. Client sends the kind 9734 JSON to the LNURL-pay endpoint as a query parameter 4. LNURL server returns a Lightning invoice 5. Client pays the Lightning invoice via the user's Lightning wallet 6. Upon payment, the LNURL server publishes a kind 9735 (zap receipt) to the relays listed in the kind 9734 7. Other clients see the kind 9735 and display the zap
Kind 9734 tags: ["p", "recipient-pubkey"] – who is being zapped ["e", "event-id"] – optional: the specific event being zapped (vs zapping a profile) ["relays", "wss://relay1...", "wss://relay2..."] – where to publish the zap receipt ["amount", "21000"] – requested amount in millisatoshis (1000 msat = 1 sat)
The zap receipt (kind 9735) is published by the LNURL server, not the sender. It contains the bolt11 invoice and a description-hash that cryptographically links it to the original zap request.
Nostr Wallet Connect (NIP-47): a standard for apps to request Lightning payments from a user's wallet without the user manually approving each payment – enables automated zapping.
Required Event Fields
Examples
{
"kind": 9734,
"pubkey": "sender-pubkey",
"tags": [
["p", "recipient-pubkey"],
["e", "target-event-id"],
["relays", "wss://relay.damus.io", "wss://nos.lol"],
["amount", "21000"] // 21 sats in millisatoshis
],
"content": "⚡ Great post!",
"id": "...",
"sig": "..."
}