Nostr

Nostr is a decentralized network protocol for a distributed social networking system. The name is an acronym for "Notes and Other Stuff Transmitted by Relays". It was designed with goals of censorship-resistance in mind.

The Nostr protocol was first written in 2020 by a Brazilian open source software developer Giovanni Torres Parra,  known by the pseudonym "fiatjaf".

Users
As of April 2023, Nostr was primarily popular with Bitcoin users. Jack Dorsey, the co-founder of Twitter, endorsed and has financially supported the development of Nostr by donating approximately $250,000 worth of bitcoin to the developers of the project.

Some Nostr apps have been banned in China.

Open protocol
As an Open protocol and FOSS project, Nostr allows for multiple different user interfaces for the same data. Multiple Nostr clients exist.

The protocol's primary form of data transport is the use of a standardized kind of WebSocket server called a Relay. Each user has a cryptographic keypair. Data on the Nostr protocol is stored in JSON blobs called Events, which are the only kind of object on the Nostr protocol.

Different extensions to the Nostr protocol are called "NIPs", for Nostr Implementation Possibilities. One of these provides integration of Nostr with the Lightning Network that operates on the Bitcoin blockchain, allowing Nostr users to send and request cryptocurrency payments (called "Zaps") to and from other users.