Proton: The privacy-first suite — end-to-end-encrypted Drive, Pass, Mail, and Calendar with a family plan, open-source clients, and Swiss jurisdiction. (Web + native apps (macOS, Windows, iOS, Android) · Proton Family ~$8–$13/mo (billed annually) across Drive/Pass/Mail/Calendar)
Cornerstone: A private operating system for the home: a family AI you can actually ask things, an encrypted vault for photos and documents that only you can open, age-graded kid access with parent oversight, a device mesh, and encrypted cold backup — all under one rule, honest custody: the server holds only ciphertext and refuses to receive your key.
✓ Mature, independently audited, open-source-client end-to-end encryption — the gold standard for "we can’t read it"
✓ Battle-tested across millions of users for years
✓ A polished, coherent suite: files, passwords, email, calendar, all E2E
✓ Swiss privacy jurisdiction and a clear, funded track record
Where Cornerstone differs
→ Proton secures your files, passwords, and mail — Cornerstone secures your whole home: a family AI, photos + documents, a device mesh, and encrypted cold backup, all under one custody model
→ No private family assistant you can actually ask questions — Cornerstone’s point is the AI, kept private
→ No age-graded kid access + parent oversight built for a household
→ No self-host / "run it on your own box" horizon
Pick Proton if…
• You want proven, audited E2E encryption today from an established company
• Your need is mainly files + passwords + private email
• Maturity and a long security track record are non-negotiable
Pick Cornerstone if…
• You want one private place for the family’s whole digital life, not just files
• You want a family AI you can ask things — kept private, key in your hands
• You want age-graded kid access with parent oversight, and a self-host horizon
Where we’re honestly behind
– Cornerstone is NEW — Proton and Apple are mature, audited, and battle-tested. If you want proven-today encryption from an established vendor, pick them, honestly
– Parts of the vision — the full device mesh, managed cold backup, self-host — are early or still being built
– No decade-deep photo library or app ecosystem yet; the depth of iteration isn’t there
– Own-family-first: this is being built for real use before it’s a polished mass-market product