Hey Product Hunt! 👋 I built Second Brain OS after getting frustrated with every productivity app storing my private journal entries on their servers. It’s a single HTML file that works in any browser on any device — mobile, PC, Mac, everything. No account, no server, no subscription. Your data never leaves your device. It has 6 sections built around the PARA method: 📥 Inbox — capture anything instantly 🎯 Projects — track with progress bars 📚 Resources — personal knowledge library 💡 Ideas — Spark → Shipped kanban board 📓 Journal — daily prompts, fully private 🔒 100% offline — private as a notebook One $17 payment. Yours forever. Happy to answer any questions about how it’s built, the PARA method, or anything else. Would love your honest feedback! 🧠

Second Brain OS

Your private Second Brain — offline

Your private Second Brain — offline