NextGraph

NextGraph is an open source ecosystem that provides solutions for end-users (a platform) and software developers (a framework), wishing to use or create decentralized apps featuring: live collaboration on rich-text documents, peer to peer communication with end-to-end encryption, offline-first, local-first, portable and interoperable data, total ownership of data and software, security and privacy. Centered on repositories containing semantic data (RDF), rich text, and structured data formats like JSON, synced between peers belonging to permissioned groups of users, it offers strong eventual consistency, thanks to the use of CRDTs. Documents can be linked together, signed, shared securely, queried using the SPARQL language and organized into sites and containers.

More info here