Open-source collaborative platform by Block, Inc. (formerly Square) — a shared workspace where humans, AI agents, workflows, Git events, and project memory coexist. Built with Rust, TypeScript, and Dart. 12.8k stars, Apache 2.0.
Self-hosted collaborative note-taking app with real-time multi-user editing via Y.js CRDT. Features rich text editor (Quill), workspaces/folders/tags, full-text search, offline support, user management, and native desktop (Electron) + Android apps. Go backend + React frontend, Docker-ready, 60 stars, MIT license.
An open-source, self-hostable alternative to Notion and Outline for collaborative note-taking, wikis, and documentation. Built with Django and React, it supports real-time collaboration, structured documents and sub-documents, with full ownership of your data.