Obsidian
Local Markdown knowledge base with bidirectional link graph. Each note is a .md file on your disk, no lock-in, no forced cloud. Community plugins for everything (AI, kanban, dataview, git sync). The link graph reveals connections between your notes as you write. Sync and Publish are paid, everything else is free for life.
Strengths
- Local-first: your notes are Markdown files on your disk, readable, editable and greppable from any tool
- Bidirectional link graph, surfaces connections between notes you didn't see when writing
- Rich plugin ecosystem (Smart Connections for AI, Dataview for queries, Git for sync, Tasks for TODOs)
- Free forever for personal use, only Sync (cross-device cloud) and Publish (public site) are paid
Limitations
- No real-time collaboration, built for one brain, not a team. For sharing, use git or Publish
- Steep plugin learning curve, power comes from composition, takes time to set up
- Proprietary (not open source), but the .md format is open, so you can leave anytime
Best for
- Storing prompts, skills and agent patterns that need to survive beyond a single Claude session
- Daily note-taking + project journal (daily notes) with linking between days and projects
- Building a personal reusable knowledge base across projects, your own private Arsenal, basically