Hello everyone! 
As a systems engineer and a long-time Obsidian user, I’ve always wanted a seamless way to feed my entire “Second Brain” into AI models like Gemini or Claude. I looked for existing tools that could handle batch-processing my notes (both from free and paid apps) into a clean, single format, but I couldn’t find exactly what I needed.
So, I decided to build it myself.
It’s called “Second Brain Joiner”. I originally designed this for my own workflow, but it worked so well that I wanted to share it with this amazing community.
What it does: It’s a lightweight Google Cloud Function that merges your vault (ZIP) into a single, AI-ready Markdown file. It ensures privacy (runs on your own cloud) and even handles things like Japanese filename encoding and integrity reporting.
Why I’m sharing this: I’ve made the source code completely Open Source on GitHub. I believe in the power of shared knowledge, so please feel free to use it, tweak it, or take it apart!
If this tool saves you even five minutes of tedious work, or helps you gain new insights from your notes, it would make me incredibly happy.
GitHub Repository: github[.]com/Hirofumi-I/second-brain-joiner
I hope this helps your digital garden grow. Happy linking!
Dicon (Hirofumi Inoue) Just a fellow tinkerer sharing what I built.
