Proton Brain: Zero-Knowledge Second Brain with Card UI (Like MyMind)
Made with Lumo...
Build a privacy-first PKM app that combines MyMind's frictionless card interface with Proton's zero-knowledge encryption.
THE PROBLEM:
Existing second-brain tools force you to choose between privacy and usability:
- Notion/Evernote: Great UX but no encryption, data harvested for AI
- Obsidian: Privacy-focused but DIY sync, no built-in AI
- MyMind: Beautiful card UI but opaque privacy practices
- Standard Notes: Encrypted but dated interface, no visual organization
THE SOLUTION:
Proton Brain—a card-based knowledge system where everything you save (notes, links, images, PDFs, emails) becomes a single unified card in an infinite grid. No folders required. No manual tagging. Just save and find later.
KEY FEATURES REQUESTED:
1. Card-Based Interface:
- All content rendered as expandable cards in a search-first grid
- No folder hierarchy—everything discoverable via search
- Reader mode for distraction-free article consumption
- Swipe gestures on mobile (archive, pin, share)
Universal Capture:
- Browser extension web clipper
- Forward emails from Proton Mail → auto-creates card
- Mobile quick-save from clipboard/screenshot
- Drag-drop from Drive/Mail into Proton Brain
Content Types:
- Text notes, web clips, images, PDFs, audio/video
- Unified card design regardless of type
- Child cards for highlights/annotations
- Source attribution preserved (click-through to original)
Privacy Guarantee:
- All cards zero-access encrypted (even Proton can't read them)
- No training on user content
- Swiss jurisdiction + no-logs policy
- Optional client-side AI inference (no server processing)
- Ghost mode for ephemeral cards
Pricing Model:
- Free tier: 100 cards limit
- Plus/Visionary: Unlimited cards included
- Leverages existing Drive storage allocation
WHY PROTON?
Proton already has the pieces: Drive (encrypted storage), Docs (editing), Lumo (AI). This unifies them into a single PKM experience that competes with Big Tech tools without compromising privacy.
TECHNICAL REFERENCES:
- UI inspiration: MyMind.com card design
- Sync: Integrate with existing Proton Drive SDK
- Search: Full-text + semantic across encrypted index
- Mobile: Native iOS/Android apps with widgets
"Notion has features. Obsidian has flexibility. Proton has trust. Now combine them."
A privacy-first second brain isn't just a nice-to-have—it's essential infrastructure for anyone who treats their thoughts and knowledge as sensitive data. Proton is uniquely positioned to deliver this because it already trusts users with their email, calendar, VPN, and password data. Extending that trust to personal knowledge would cement Proton as the complete alternative to Big Tech productivity suites.
VOTE IF YOU WANT: A beautiful, private second brain that doesn't sell your data.
voyager2bird
shared this idea
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voyager2bird
commented
Thanks for your comment. I think the OP lays out the key features well, and I think totally doable now with Lumo connected to Drive. A web-clipper in itself would be a welcomed tool to add content to Drive with Lumo auto-tag the items, then it's just the UI to visualize, search, link. A to-do list is a big request and I think that just becomes another "card" in the space. I think users would actually find this approach attractive and very useful if done well, it would flatten the folder structure, so it's a different way to view one's assets in Drive.
I've added another post to the Lumo category: https://protonmail.uservoice.com/forums/932842-lumo/suggestions/51640486-lumo-ai-powered-card-organization-for-proton-drive
I welcome your comments and support on that idea as well.
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Sanchizes chinazes commented
The idea of a "Proton Brain" as a zero-knowledge second brain with Car... sounds like a fascinating and ambitious concept! A privacy-focused tool for storing and organizing personal knowledge would be a great addition to the Proton ecosystem. It could offer a secure alternative to mainstream note-taking apps. For those who value privacy and security in their digital tools, you might also appreciate the transparent environment at https://nvcasino-fra.net/ . What kind of features would you expect from such a service?