Obsidian

In one sentenceA note-taking app that stores every note as a plain Markdown file on your own computer, which makes it a perfect "second brain" for AI to read.

What it means

Obsidian keeps your notes in a folder called a vault. Each note is a Markdown file, notes link to each other with double square brackets, and a graph view shows how your ideas connect.

Because the vault is just files on your disk, AI agents can read it, search it and write to it directly: Claude Code or Codex pointed at the folder, an MCP connector, or plugins inside Obsidian. Your notes become long-term Memory and context for AI.

How to use it

• Save meeting notes, client details, content ideas and your best posts in one vault, then ask AI questions across all of it.
• Have an AI agent write daily summaries or research straight into the vault so everything lands in one place.
• For a very large vault, a Vector Database or RAG plugin helps AI find the right notes fast.
• Notes are local by default, which is good for privacy; back up the vault (Obsidian Sync, iCloud, Git).

Related terms

Markdown Knowledge Base RAG Vector Database Memory