I Built a Personal Second Brain with Markdown Files and Claude Code — Here's How

The Inspiration I saw Andrej Karpathy's viral post about using LLMs to build personal knowledge bases — no vector database, no chunking pipeline. Just markdown files, Obsidian, and Claude Code. The core idea blew my mind: Create a folder with raw/ and wiki/ subfolders Drop in source documents, articles, transcripts Tell the LLM to ingest the raw files and build wiki pages with relationships, tags, and backlinks I immediately thought: I need to build this, but better. What I Built I took Karpathy's concept and extended it into a full-featured Personal Second Brain with several improvements: The Original Concept (Credit: Andrej Karpathy) Markdown-based wiki with raw/ → wiki/ pipeline LLM reads source material and generates structured wiki pages Pages link to each other via [[backlinks]] Graph view in Obsidian shows connections My Improvements 1. Multi-Format Ingestion The original handles text/markdown. I added support for: PDF files → converted via Marker to markdown before processing Y