An agent that turns your bookmarks into a linked wiki
It exists because filing and linking your saved articles is boring work that humans abandon after roughly two weeks.

What it does
This repo is a guide, starter vault, and agent toolkit for an AI-maintained personal knowledge base. You save articles, transcripts, and chat exports to a raw/ folder; an agent ingests them into a wiki of linked markdown pages you own. The vault is designed to get better as it grows because new sources update existing pages rather than accumulating in silos.
The interesting bit The system enforces a hard rule: nothing counts as ingested until it is linked into the graph. When sources contradict each other, the agent records both positions with dates rather than overwriting, preserving a history of what you believed. The whole setup splits knowledge into two layers—what you know (the wiki) and what you are doing (projects)—that feed each other.
Key highlights
- 18 agent skills, 72 slash commands, and 6 subagents handle workflows from ingestion to scheduled maintenance.
- Ships with a starter vault template, dependency-free Python scripts for link checking and graph export, and a 77-page guide.
- Five compact “tracks” cover adjacent topics like GraphRAG, agent harnesses, and eval engineering.
- No vector database by default; retrieval relies on structured pages and typed links until your corpus justifies RAG.
Caveats
- The graph is intentionally sparse at small scale: the README warns it is “not interesting at five pages and it is hard to look away from at fifty.”
- Explicitly scoped for personal use; the README states it is “not for team wikis” and “not a Notion replacement.”
- It will not organize a vault you never add to; the system requires continuous feeding.
Verdict A strong fit if you read heavily but retain less than you want, and you are willing to feed an agent. Skip it if you are looking for a collaborative workspace or a zero-effort archive.
Frequently asked
- What is undefined-ui/second-brain-os?
- It exists because filing and linking your saved articles is boring work that humans abandon after roughly two weeks.
- Is second-brain-os open source?
- Yes — undefined-ui/second-brain-os is open source, released under the MIT license.
- What language is second-brain-os written in?
- undefined-ui/second-brain-os is primarily written in HTML.
- How popular is second-brain-os?
- undefined-ui/second-brain-os has 580 stars on GitHub.
- Where can I find second-brain-os?
- undefined-ui/second-brain-os is on GitHub at https://github.com/undefined-ui/second-brain-os.