GOODBYE Notion. GOODBYE Roam. GOODBYE EXPENSIVE Mem AI subscriptions.

Claude Code and Obsidian just killed the entire second brain industry.

Pick one topic you actually care about. AI, your niche, a course, anything.

Open Obsidian. Create a vault. Add 4 folders: raw, wiki, outputs, templates.

Install Web Clipper. Point it at raw/inbox.

Open Claude Code inside the vault. Run /init.

Drop this in claude.md:

raw/ holds source material, never edit it.

wiki/ is the living knowledge layer you maintain.

outputs/ is where good answers get saved.

When I add a source, ingest it into the wiki and update the index.

When I ask a question, read the wiki first and save the answer to outputs.

Claude reads the vault. Builds the wiki. You browse it in Obsidian.

That’s the basic version.

What I used it for

I had 200+ articles bookmarked on AI agents. Retained almost none of it.

So I stopped bookmarking and built a vault instead.

Claude ingested 30 articles into one folder. Concepts got their own pages. Sources cross-referenced. Contradictions flagged on the spot.

Then I asked it where my sources disagreed on agent memory. Got a 700-word brief saved to outputs/ in under a minute.

That brief became the spine of my next article.

Results

• Full setup in under 10 minutes from one empty folder

• One vault for one topic beats one giant catch-all every time

• Skills replace bloated prompts (ingest-source, kb-report, kb-lint, make-slides)

• Weekly loop: clip Mon, ingest Tue, hard question Wed, brief Thu, lint Fri

Notion AI runs $20/month per user and still loses your context between chats.

Roam Research costs $165/year and the graph view stops mattering the day you stop writing.

Mem AI is $10/month and your notes sit in their cloud, not on your hard drive.

Obsidian is free. Claude Code runs in your terminal. Your vault stays on your own machine.

A folder that gets smarter every week. That’s the whole point.

——

Opinion AI Claude + Obsidian guides

• Karpathy’s AI Second Brain: A Guide to Building Your Own — emergingai.substack.com…

• Claude Code + Obsidian Guide: Karpathy’s AI Second Brain, Continued — emergingai.substack.com…

• Claude Changed the May 2026 Way to Build a Second Brain — emergingai.substack.com…

——

♻️ Restack if you liked it.

🔔 Subscribe for more practical AI workflows.