• Nostr Relays
  • What Relays Do
  • Relay Architecture
  • Relay Types
    • Public Relays
    • Private Relays
    • Paid Relays
    • Specialized Relays
  • Relay Information (NIP-11)
  • My Relays
  • Relay Policies
    • Kind Filtering
    • Rate Limiting
    • Content Moderation
  • Relay Software
  • Attacking & Defending
    • Attacks on Relays
    • Defenses for Users
  • Relay Selection Best Practices
  • Running Your Own Relay
  • Relay Discovery

§Nostr Relays

Dumb pipes. Smart network. Relays are the infrastructure layer that makes Nostr work.

§What Relays Do

Relays are WebSocket servers that:

1. Accept events from clients (EVENT)
2. Store events (optionally, based on kind policy)
3. Forward events to subscribers (REQ → EVENT stream)
4. Send notices for errors, rate limits, etc.

That’s it. No logic. No feeds. No algorithms. Just store and forward.

§Relay Architecture

  CLIENT A                    RELAY                      CLIENT B
     │                         │                           │
     │──EVENT(kind:1)────────▶│                           │
     │                         │──store───────────────────│
     │                         │                           │
     │                         │◄──REQ(kinds:[1])─────────│
     │                         │──EVENT (match)──────────▶│
     │                         │──EVENT (match)──────────▶│
     │                         │──EOSE────────────────────▶│

§Relay Types

§Public Relays

• Anyone can connect
• Anyone can publish
• Anyone can read
• Free or paid

§Private Relays

• Access controlled
• Whitelisted pubkeys
• Invite-only
• Often for DMs or private communities

§Paid Relays

• Pay-per-event or subscription
• Higher quality (less spam)
• Often used for write access

§Specialized Relays

• Search relays (kind 10007): indexed search
• DM relays (kind 10050): dedicated to private messages
• Read relays: optimized for content delivery
• Write relays: optimized for event acceptance

§Relay Information (NIP-11)

Every relay should serve metadata at its WebSocket endpoint:

GET wss://relay.damus.io
→ NIP-11 JSON document

{
  "name": "Damus Relay",
  "description": "Public relay for Damus users",
  "pubkey": "7e2...",
  "contact": "damus@example.com",
  "supported_nips": [1, 2, 4, 9, 11, 12, 15, 16, 20, 22, 28, 33, 40],
  "software": "strfry",
  "version": "0.9.6",
  "limitation": {
    "max_message_length": 16384,
    "max_subscriptions": 20,
    "max_filters": 100,
    "max_limit": 500,
    "max_subid_length": 100,
    "min_prefix": 4,
    "max_event_tags": 100,
    "created_at_lower_limit": 946684800,
    "created_at_upper_limit": 2147483647
  },
  "payments_url": "https://...",
  "fees": {
    "admission": [{ "amount": 1000000, "unit": "msats" }],
    "publication": [],
    "subscription": [{ "amount": 5000000, "unit": "msats", "period": 2592000 }]
  }
}

§My Relays

wss://relay.damus.io       — Public, high traffic
wss://nos.lol              — Public, reliable
wss://relay.nostr.band     — Public, searchable
wss://relay.primal.net     — Public, Primal backend
wss://nostr.mom            — Public
wss://purplepag.es         — Indexing relay

Managed via kind 10002:

{
  "kind": 10002,
  "tags": [
    ["r", "wss://relay.damus.io"],
    ["r", "wss://nos.lol"],
    ["r", "wss://relay.nostr.band", "read"],
    ["r", "wss://relay.primal.net"],
    ["r", "wss://nostr.mom"],
    ["r", "wss://purplepag.es", "read"]
  ]
}

§Relay Policies

Relays decide what to store/forward. Common policies:

§Kind Filtering

Store: kinds 0, 1, 3, 5, 6, 7, 30023, 9735
Reject: kinds 4, 23194, 23195  (ephemeral)
Ignore: kinds 20000-29999 (by design)

§Rate Limiting

Max events per minute: 10-100
Max subscription filters: 20-100
Max subscription duration: infinite or time-limited

§Content Moderation

Some relays block content. Some don’t. Pick relays that match your values.

§Relay Software

§Attacking & Defending

§Attacks on Relays

• Spam: Flood with junk events → rate limiting, POW (NIP-13), paid relays
• DDoS: Overwhelm with connections → connection limits, CDN
• Storage exhaustion: Fill disk → kind filtering, retention limits
• Content injection: Forge events → sig verification on acceptance

§Defenses for Users

• Multiple relays: Publish to 3-5 relays for redundancy
• Read relays: Use separate relays for reading
• Private relays: Run your own for sensitive content
• DM relays: Dedicated relay for DMs (kind 10050)

§Relay Selection Best Practices

1. Audit your relay list: Know who runs each relay
2. Diversify: 5-8 relays across different operators
3. Separate concerns: Write relays ≠ Read relays ≠ DM relays
4. Keep it small: NIP-65 recommends 2-4 of each type
5. Spread kind 10002: Publish your relay list everywhere

§Running Your Own Relay

# strfry - fast C++ relay
git clone https://github.com/hoytech/strfry
cd strfry && make setup-golpe
make -j4
./strfry relay

Benefits:

• Full control over your data
• No censorship by third parties
• Can archive all your events
• Learn the protocol from the inside

§Relay Discovery

Finding relays:

1. Purple Pages (purplepag.es): Community-curated relay index
2. nostr.watch: Relay monitoring + uptime stats
3. User follow lists: See what relays followed users use
4. kind 10002: Everyone’s relay list metadata
5. NIP-11: Ask a relay for its info