Nostr

Nostr Protocol & nostr-tools

Comprehensive reference for the Nostr protocol and the nostr-tools JavaScript library.

Protocol Fundamentals

Events

All data in Nostr is an event — a signed JSON object:

{
  "id": "<32-byte hex SHA256 of serialized event>",
  "pubkey": "<32-byte hex public key>",
  "created_at": "<unix timestamp in seconds>",
  "kind": "<integer>",
  "tags": [["<name>", "<value>", "..."]],
  "content": "<string>",
  "sig": "<64-byte hex schnorr signature of id>"
}

ID calculation: SHA256(JSON.stringify([0, pubkey, created_at, kind, tags, content])) — compact JSON, no spaces.

Signature: Schnorr (BIP-340) on secp256k1, signing the 32-byte event ID.

Event Kind Ranges

Common kinds: 0 metadata, 1 text note, 3 contacts, 5 deletion, 6 repost, 7 reaction, 9 group message (NIP-29), 9735 zap receipt, 10002 relay list, 30023 article.

See references/event-kinds.md for the full list.

Tags

["e", "<event-id>", "<relay-url>", "<marker>"]  — event reference
["p", "<pubkey>", "<relay-url>"]                 — profile reference
["a", "<kind>:<pubkey>:<d-tag>", "<relay-url>"]  — replaceable event ref
["d", "<identifier>"]                            — parameterized replaceable ID
["t", "<hashtag>"]                               — hashtag
["r", "<url>"]                                   — web resource / relay

NIP-10 markers for threading: "root", "reply", "mention".

Client-Relay Communication (WebSocket)

Client sends: ["EVENT", <event>], ["REQ", <sub_id>, <filter>, ...], ["CLOSE", <sub_id>], ["AUTH", <event>]

Relay sends: ["EVENT", <sub_id>, <event>], ["OK", <event_id>, <bool>, <msg>], ["EOSE", <sub_id>], ["CLOSED", <sub_id>, <msg>], ["NOTICE", <msg>], ["AUTH", <challenge>]

Filters

{
  "ids": ["<hex>"],
  "authors": ["<hex>"],
  "kinds": [1, 7],
  "#e": ["<event-id>"],
  "#p": ["<pubkey>"],
  "#t": ["<hashtag>"],
  "since": 1704067200,
  "until": 1704153600,
  "limit": 50,
  "search": "query"
}

• Array fields are OR'd; different fields are AND'd
• ids and authors support prefix matching
• Always set reasonable limit (50-500)

nostr-tools Library

Key Management & Encoding (NIP-19)

import { generateSecretKey, getPublicKey } from 'nostr-tools/pure';
import { nip19 } from 'nostr-tools';

const sk = generateSecretKey();          // Uint8Array
const pk = getPublicKey(sk);             // hex string

// Encode
const npub = nip19.npubEncode(pk);       // npub1...
const nsec = nip19.nsecEncode(sk);       // nsec1...
const note = nip19.noteEncode(eventId);  // note1...

const nprofile = nip19.nprofileEncode({ pubkey: pk, relays: ['wss://...'] });
const nevent = nip19.neventEncode({ id, relays, author, kind });
const naddr = nip19.naddrEncode({ identifier, pubkey, kind, relays });

// Decode
const { type, data } = nip19.decode(npub); // type: 'npub', data: hex

Creating & Signing Events

import { finalizeEvent, verifyEvent } from 'nostr-tools/pure';

const event = finalizeEvent({
  kind: 1,
  created_at: Math.floor(Date.now() / 1000),
  tags: [['t', 'nostr']],
  content: 'Hello Nostr!'
}, secretKey);

const valid = verifyEvent(event); // true/false

Relay Communication (SimplePool)

import { SimplePool } from 'nostr-tools/pool';

const pool = new SimplePool();
const relays = ['wss://relay.damus.io', 'wss://nos.lol'];

// Subscribe
const sub = pool.subscribeMany(relays, [filter], {
  onevent(event) { /* handle event */ },
  oneose() { /* end of stored events */ }
});
sub.close(); // always close when done

// Query (returns Promise)
const events = await pool.querySync(relays, filter);
const event = await pool.get(relays, { ids: [eventId] });

// Publish
await Promise.allSettled(pool.publish(relays, signedEvent));

// Cleanup
pool.close(relays);

Direct Relay Connection

import { Relay } from 'nostr-tools/relay';

const relay = await Relay.connect('wss://relay.damus.io');

const sub = relay.subscribe([filter], {
  onevent(event) { /* ... */ },
  oneose() { sub.close(); }
});

await relay.publish(signedEvent);
relay.close();

Encryption

// NIP-44 (preferred)
import { nip44 } from 'nostr-tools';

const conversationKey = nip44.getConversationKey(secretKey, recipientPubkey);
const ciphertext = nip44.encrypt('Hello!', conversationKey);
const plaintext = nip44.decrypt(ciphertext, conversationKey);

// NIP-04 (legacy, avoid for new code)
import { nip04 } from 'nostr-tools';

const ct = await nip04.encrypt(secretKey, recipientPubkey, 'Hello!');
const pt = await nip04.decrypt(secretKey, senderPubkey, ct);

NIP-05 DNS Identifiers

import { nip05 } from 'nostr-tools';

const profile = await nip05.queryProfile('alice@example.com');
// { pubkey: '...', relays: ['wss://...'] }

NIP-10 Thread Parsing

import { nip10 } from 'nostr-tools';

const parsed = nip10.parse(event);
// { root, reply, mentions, profiles }

Key NIPs Reference

See references/nips-overview.md for comprehensive NIP documentation.

Common Patterns

Reply with NIP-10 threading

const reply = finalizeEvent({
  kind: 1,
  created_at: Math.floor(Date.now() / 1000),
  tags: [
    ['e', rootEventId, '', 'root'],
    ['e', parentEventId, '', 'reply'],
    ['p', parentAuthorPubkey]
  ],
  content: 'Great post!'
}, secretKey);

NIP-65 relay list

// Fetch user's relay preferences
const [relayList] = await pool.querySync(relays, {
  kinds: [10002], authors: [pubkey]
});

const readRelays = [], writeRelays = [];
for (const [tag, url, mode] of relayList.tags) {
  if (tag !== 'r') continue;
  if (!mode || mode === 'read') readRelays.push(url);
  if (!mode || mode === 'write') writeRelays.push(url);
}

Reconnection with backoff

let delay = 1000;
const connect = () => {
  const ws = new WebSocket(relayUrl);
  ws.onopen = () => { delay = 1000; resubscribe(); };
  ws.onclose = () => {
    setTimeout(connect, delay);
    delay = Math.min(delay * 2, 30000);
  };
};

Security Essentials

• Never expose nsec in code, logs, or network requests
• Always verify signatures before trusting event data
• Use NIP-44 for encryption (NIP-04 is deprecated)
• Sanitize content before rendering (XSS prevention)
• Prefer NIP-07 (browser extensions) over handling raw keys

See references/common-mistakes.md for a comprehensive list of pitfalls.

Reference Files

• references/nips-overview.md — Detailed descriptions of all standard NIPs
• references/event-kinds.md — Complete event kinds reference with examples
• references/common-mistakes.md — 30 common implementation mistakes and fixes

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