NIP-333

Verify Bitcoin without trusting anyone. Bitcoin block headers are 80-byte cryptographic proofs. NIP-333 defines a single replaceable Nostr event (kind 33333) carrying the latest twelve headers — small enough for any relay, fresh enough for any wallet, and verifiable by anyone: proof-of-work checks itself, so the publisher is a convenience, never an authority.

Latest Headers connecting…

mainnettestnet4

How It Works

• Compact: twelve 80-byte headers — 960 bytes of proof covering roughly two hours of blocks.
• Replaceable: parameterized replaceable events, one stream per network (d: btc, d: tbtc4, …) — relays store only the newest version. Subscribe once, stay synced.
• Trustless: every header is verified on receipt — proof-of-work against its own target, each header linking to the previous. This page does exactly that, in your browser, before showing you anything.
• Bootstrap-friendly: events carry u tags pointing at archive and epoch data sources, so a fresh client can sync the full header chain.

Example Event

The event from the specification: one replaceable event per network, the twelve newest headers as 1,920 hex characters of content, and u tags for the archive a fresh client syncs from.

{
  "kind": 33333,
  "pubkey": "cccccccc829b802b7bf52d43edf7cfe62ac89f332a318b6826ac8bd6e73660da",
  "created_at": 1733356800,
  "tags": [
    ["d", "btc"],
    ["n", "btc"],
    ["tip", "875011"],
    ["u", "https://github.com/bitcoincc/bitcoin-epochs/releases/latest/download/btc.archive.bin"],
    ["u", "https://github.com/bitcoincc/bitcoin-current/releases/latest/download/btc.current.bin"],
    ["alt", "Bitcoin headers 875000-875011"]
  ],
  "content": "00e0ff3f…[1920 hex chars: twelve 80-byte headers]…",
  "id": "…",
  "sig": "…"
}

Subscribe via Nostr

["REQ", "headers", {
  "kinds": [33333],
  "#d": ["btc"],
  "limit": 1
}]

Networks: btc (mainnet), tbtc3 (testnet3), tbtc4 (testnet4). See the full specification.

Implementations

• bitcoin.cc — realtime header dashboard and SPV infrastructure
• btc-archive — full header chain, epoch files
• btc-current — current epoch snapshot