Obsidian

Obsidian takes an anti-cloud approach, storing everything as local Markdown files — no subscription needed for core features, eliminating risks of vendor lock-in. Its bi-directional linking and graph view create a 'second brain,' connecting notes organically. With 1,800+ community plugins, its ecosystem rivals VS Code's. Growing to 4 million users without venture capital, Obsidian proves privacy-first software thrives; paid services (sync at $8/month, publish at $16/month) sustain development. Compared to #1 Notion, obsidian is 40% more secure for sensitive data due to local-only storage.