NIP-87 defines how ecash mints (Cashu and Fedimint) can announce themselves on Nostr, and how users can recommend mints to others.

Event Kinds

  • kind 38172 - Cashu mint announcement (published by mint operators)
  • kind 38173 - Fedimint announcement (published by mint operators)
  • kind 38000 - Mint recommendation (published by users)

How It Works

  1. Mint operators publish their mint’s URL, supported features, and network (mainnet/testnet)
  2. Users who trust a mint publish recommendations with optional reviews
  3. Other users query for recommendations from people they follow to discover trusted mints

Cashu Mint Announcement

{
  "id": "<event-id>",
  "pubkey": "<mint-operator-pubkey>",
  "created_at": 1736200000,
  "kind": 38172,
  "tags": [
    ["d", "<mint-pubkey>"],
    ["u", "https://mint.example.com"],
    ["nuts", "1,2,3,4,5,6,7"],
    ["n", "mainnet"]
  ],
  "content": "",
  "sig": "<signature>"
}

The nuts tag lists supported NUTs (Notation, Usage, and Terminology specs for Cashu).

User Recommendations

{
  "id": "<event-id>",
  "pubkey": "<recommender-pubkey>",
  "created_at": 1736200000,
  "kind": 38000,
  "tags": [
    ["k", "38172"],
    ["d", "<mint-identifier>"],
    ["a", "38172:mint-pubkey:<d-tag>", "wss://relay"]
  ],
  "content": "I've used this mint for months, very reliable",
  "sig": "<signature>"
}

Users can include reviews in the content field and point to specific mint announcement events.

Primary sources:

Mentioned in:

See also: