Q&A: What is a Nostr relay and how do I pick one?

Question:

What is a Nostr relay and how do I pick one?

Answer:

What is a Nostr relay?

A relay is the network layer of Nostr — a server that accepts, stores, and forwards signed JSON events over a WebSocket connection (wss://). Think of it as a dumb pipe plus a database, not a social network.

How it works:

1. Your client opens a WebSocket to a relay.
2. It publishes events (["EVENT", <event>]) or subscribes to events matching filters (["REQ", <sub-id>, <filter>]).
3. The relay stores events and pushes new matching ones to subscribers, signaling the end of stored history with ["EOSE", ...] and acknowledgments with ["OK", ...].

Key point: relays are untrusted. Your client verifies every event signature locally (secp256k1), so a malicious relay can censor or withhold data but cannot forge or alter your events. This is why Nostr is censorship-resistant rather than censorship-proof — you stay portable and can move relays without losing your identity, since your identity is your keypair, not an account on a server.

How to pick one

Use a small, intentional set — not dozens. NIP-65 guidance says keep each list to 2–4 relays; a common practical rule of thumb is 5–10 diverse relays total, mixing free public and paid ones for reach and reliability.

Use read/write separation (NIP-65). You advertise your relay preferences in a replaceable kind:10002 event, with optional markers:

{
  "kind": 10002,
  "tags": [
    ["r", "wss://relay.damus.io"],                      // read + write
    ["r", "wss://my-relay.example.com", "write"],       // where you publish
    ["r", "wss://inbox.example.com", "read"]            // where you expect mentions
  ],
  "content": ""
}

• No marker → both read and write
• "write" → relays where you post your own events (clients fetch your events from your write relays)
• "read" → relays where you’re tagged (clients fetch events about you from your read relays)

Criteria to evaluate:

• Reliability / uptime — does it stay online and respond quickly?
• Moderation posture — some relays are open to everything, others filter spam or certain content. Pick a mix so no single policy silences you.
• Transparency — check the relay’s NIP-11 metadata (fetched via an HTTP Accept: application/nostr+json request) for its operator, description, and supported features.
• Feature support — e.g. NIP-50 full-text search, or paid/“high-quality” relays with write restrictions.
• Privacy — relays can see your IP address, so use Tor or a VPN if that matters to you.

For private messages, note a separate mechanism: NIP-17 uses a kind:10050 event listing relays where you receive encrypted (gift-wrapped) messages. Senders look up your kind:10050 list and publish only to those relays, keeping DMs off your public relays.

Common bootstrap relays (from the Nostr Mail client, useful as a starting point):
wss://relay.damus.io, wss://nos.lol, wss://relay.primal.net, wss://relay.coinos.io

Sources: NIP-01, NIP-65 (nips.nostr.com/65), and the Nostr LLM Wiki page on relays.

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