Obsidian

Obsidian is my second brain. It is a local-first, Markdown-based knowledge management app that stores everything as plain text files on disk. No vendor lock-in, no sync service dependency, and no proprietary format.

The killer feature is bidirectional linking. Every note can reference any other note, and the graph view shows you how ideas connect. Over time this becomes genuinely useful — a question asked in one note links to research found in another, which links to a code snippet in a third.

I use Obsidian for capturing learning notes, tracking project context that does not belong in code comments, and writing long-form drafts before they move to a real document. The Templater and Dataview plugins are particularly powerful for creating structured note workflows.

The community plugin ecosystem is vast. Canvas, Daily Notes, and the Zotero integration are the plugins I use most heavily. If you do any kind of knowledge work alongside writing code, Obsidian will change how you think about organising information.