Karpathy sketched the second brain. these 7 open-source repos already built it for Obsidian + Claude Code 250,000+ GitHub stars between them, and every one is free to clone sorted by stars: 1. graphify - 134k stars turns your codebase, docs, SQL schemas and PDFs into one knowledge graph you can query ↳ https://t.co/w6eAmbYdCM 2. Understand-Anything - 88k stars maps any codebase into an interactive knowledge graph you can click through ↳ https://t.co/yc0VHTSLFG 3. claude-obsidian - 15.8k stars a second brain that organizes itself: drop in a source, Claude Code files it ↳ https://t.co/6hPHg2bMvT 4. obsidian-second-brain - 4.9k stars long-term memory for Claude Code, stored as plain markdown in your vault ↳ https://t.co/1yEv4QxRJW 5. mcp-obsidian - 4.5k stars one MCP server and Claude can read, search and write your whole vault ↳ https://t.co/ZPKYoGjcCn 6. claudesidian - 2.6k stars a starter vault designed around Claude Code from the first note ↳ https://t.co/VxefWthEeW 7. second