NIP-19 defines human-friendly formats for sharing Nostr identifiers. These bech32-encoded strings are used for display and sharing but are never used in the protocol itself (which uses hex).

How It Works

Raw hex keys are error-prone to copy and visually indistinguishable. Bech32 encoding adds a human-readable prefix and checksum, making it clear what type of data you are looking at and catching many copy errors.

The basic forms encode a single 32-byte value:

  • npub - Public key (your identity, safe to share)
  • nsec - Private key (keep secret, used for signing)
  • note - Event ID (references a specific event)

Example: The hex pubkey 3bf0c63f... becomes npub180cvv07tjdrrgpa0j7j7tmnyl2yr6yr7l8j4s3evf6u64th6gkwsyjh6w6.

The extended forms use TLV encoding so they can carry lookup hints alongside the identifier itself:

  • nprofile - Profile with relay hints
  • nevent - Event with relay hints, author pubkey, and kind
  • naddr - Addressable event reference with pubkey, kind, d tag, and relay hints

Why It Matters

Relay hints are not authoritative, but they often decide whether a client can fetch a shared event on the first try. This is why nevent, nprofile, and naddr are usually better sharing formats than bare note or npub values when content lives outside the recipient’s current relay set.

Another practical distinction is stability. note points to one immutable event id, while naddr points to an addressable event that can be replaced over time. For long-form content, calendars, or repository announcements, naddr is usually the right link type.

Implementation Notes

  • Use bech32 only for human interfaces: display, copy/paste, QR codes, URLs
  • Never use bech32 formats in protocol messages, events, or NIP-05 responses
  • All protocol communication must use hex encoding
  • When generating nevent/nprofile/naddr, include relay hints for better discoverability
  • Treat nsec as secret material everywhere. A client should never display it by default, log it, or include it in support exports

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