Nostr Relay WebSocket Interface

A Nostr relay is a WebSocket server that accepts signed events, stores them subject to its own policy, and responds to subscription filters from clients. The relay surface is intentionally minimal: no accounts, no shared state, no canonical ordering. Operators choose retention, content policy, paid-access, and authentication (NIP-42) independently. Reference implementations include strfry (C++), nostream (TypeScript), and khatru (Go).