NIP-05 maps Nostr public keys to human-readable internet identifiers like user@example.com. It gives users a DNS-backed identity hint that clients can verify over HTTPS.

How It Works

A user claims an identifier by adding a nip05 field to their profile metadata. The identifier follows the format name@domain. Clients verify the claim by fetching https://domain/.well-known/nostr.json and checking that the name maps to the user’s pubkey.

The JSON file at the well-known path contains a names object mapping local names to hex pubkeys:

{
  "names": {
    "alice": "abc123...",
    "bob": "def456..."
  }
}

When verification succeeds, clients can display the identifier instead of or alongside the npub. Some clients show a verification indicator, while others show the identifier as plain text and leave trust decisions to the reader.

Trust Model

NIP-05 is not a global username registry. It proves control of a domain name and web server path, not legal identity or long-term account continuity. If a domain owner changes the mapping later, clients will verify the new mapping unless they keep prior state.

That makes NIP-05 useful for discoverability and reputation, but weaker than users often assume. A good client should treat it as verified domain control, not proof that a person or organization is who they claim to be.

Relay Hints

The nostr.json file can optionally include a relays object mapping pubkeys to arrays of relay URLs. This helps clients discover where to find events from a particular user.

Interop Notes

The lowercase requirement matters more than it looks. Mixed-case names or pubkeys can work in one implementation and fail in another, so current clients should expect lowercase names and lowercase hex keys in nostr.json.

Another practical detail is the special _ name, which lets a domain map the bare identifier form like _@example.com or just example.com in clients that support it. Not every client exposes that form the same way, so users still get the most consistent results with explicit name@domain identifiers.

Implementation Status

Most major clients support NIP-05 verification:

  • Damus, Amethyst, Primal display verified identifiers
  • Many relay services offer NIP-05 identifiers as a feature
  • Numerous free and paid NIP-05 providers exist

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