Logseq

Logseq is a privacy-first, open-source platform for knowledge management and collaboration. It is used for notes, projects, tasks, and ideas, with an emphasis on privacy, longevity, and user control. It supports Markdown and Org-mode, and includes tools for PDF annotation and task management.

Notes are organized as graphs, including newer DB graphs in the Database version. The DB version adds RTC, a sync approach for syncing graphs between devices or collaborating with others. Logseq also has plugins and themes for customization, plus mobile apps with access to most desktop features.

The Database version is still in beta and its new mobile app and RTC are in alpha, so data loss is possible at this stage. Back up your graphs with automated backups or regular SQLite exports, and keep a dedicated test graph for non-critical work until these versions stabilize.