Obsidian

Obsidian is a note-taking application for building a personal knowledge base. Notes are plain Markdown files kept in a folder on the user's own device, so they stay readable outside the app and work offline. Users connect notes with links, browse backlinks and a graph view, and organize visual boards with Canvas. Community plugins and themes adapt the app to uses such as journaling, research, writing or project tracking. Two paid services complement the app: Obsidian Sync keeps notes in step across devices with end-to-end encryption and version history, and Obsidian Publish turns selected notes into a public website or wiki. It is used by writers, researchers, developers and students.