Nostrex is a Nostr relay written in Elixir. It is designed to be highly scalable and very operator-friendly to empower the rapid adoption of the Nostr protocol. Nostrex has a number of qualities and features that make it a compelling relay implementation.
The Erlang OTP gives us the primitives necessary to build high-throughput, concurrent high-uptime message routing software. The OTP has been hardened and optimized over decades and a single beefy server should be able to handle millions of concurrent connections.
One of the major bottlenecks of scaling a relay are the database operations. Nostrex has already implemented a number of optimizations at the DB level, including partitioning by Event created_at timestamps to keep table sizes in check.
Nostrex takes full advantage of the Erlang OTP's ETS in-memory datastore as the global state for a fast-filtering algorithm that efficiently matches events to filters instead of brute-forcing and checking each new event against every registered filter. There is still a lot of room to improve this algo.
The Erlang OTP allowed Whatsapp to scale to billions of users with a small team of engineers. With the right optimizations I feel confident that a single beefy Nostr instance will be able to power millions of concurrent connections.
IP-based rate limiting for sockets, filters, and events is implemented and configurable.
Load testing tooling is located in the /load_testing repo.
- Validate event signatures (waiting on Bitcoinex lib updates)
- Remove unused boilerplate code
- Add prometheus monitoring
- Create better filter tests to uncover any remaining edge cases
- NIP 01 Basic protocol flow description
- NIP 02 Contact List and Petnames
- NIP 04 Encrypted Direct Message
- NIP 09 Event Deletion
- NIP 11 Relay Information Document
- NIP 12 Generic Tag Queries
- NIP 15 End of Stored Events Notice
- NIP 20 Command Results
- NIP 40 Expiration Timestamp