Events
Full event CRUD across all three views. Each event carries title, description, location, start/end, all-day toggle, color, reminder minutes and status (confirmed / tentative / cancelled).
Calendar fits naturally into this flow.
Propose meeting times to other members, they counter-propose. Share a free/busy/propose/manage view of your calendar with specific contacts. Accept shared proposals in-app.
Calendar fits naturally into this flow.
Events are encrypted client-side. EU-hosted, never sold or profiled. Reminders fire from your device, not from a server that tracks when you open which event.
Calendar fits naturally into this flow.
Every UltimaOS app shares the same post-quantum cryptographic stack, so the security properties below apply uniformly. App-specific considerations are noted where they apply.
All authentication and key exchange uses NIST-standardized ML-DSA-65 (FIPS 204) signatures and ML-KEM-768 (FIPS 203) key encapsulation. There is zero RSA, zero elliptic-curve, zero classical-only crypto in the authentication path. Defeats store-now-decrypt-later attacks.
Every payload is encrypted in your browser using XChaCha20-Poly1305 (RFC 8439) with a 192-bit nonce and a Poly1305 authentication tag. The plaintext exists only in your tab's memory. When you close the tab, the plaintext is gone.
The UltimaOS server only ever stores ciphertext and public keys. We cannot read your data — by design, not by promise. There is no encryption backdoor, no master key, no key escrow.
Your private key is derived from your passphrase using Argon2id with high parameters. New devices derive the same key locally and can decrypt your entire history. The passphrase is never sent to the server — it is verified by an ML-DSA-65 signature on a server-issued challenge.
UltimaOS runs in any modern browser — Chrome, Firefox, Safari, Edge. Nothing to install. Sign in with your passphrase-derived key, or restore from a 3-of-5 social recovery if you are on a new device.
Every action — sending a message, uploading a file, creating a task, scheduling an event — is encrypted with XChaCha20-Poly1305 and authenticated with an ML-DSA-65 signature before any byte crosses the network boundary.
The UltimaOS server keeps an opaque blob per account and per conversation. When you open Calendar, the encrypted blobs are streamed to your device, decrypted locally, and rendered. The server never sees plaintext.
Any change you make is encrypted and uploaded; every other device you are signed in on pulls the new ciphertext and decrypts it. Live multi-device sync, with the cryptography guarantee that only your devices can read it.
Propose meeting times to specific contacts. They counter-propose in Calendar.
Schedule sends a calendar invite encrypted by Mail. Recipients RSVP from their Calendar.
Tasks inherit their due date from Calendar events. Completing one unlinks the other.
Calendar events attach to Boards cards as milestones. Drag a card onto a date to set due.
UltimaOS runs in Chrome, Firefox, Safari and Edge. Nothing to install. Sign in with your passphrase to derive your private key locally.
The launcher shows every app. Calendar is right there with its capsule video preview. Click to open.
Calendar works alone, but it shines when combined with the rest of the UltimaOS apps. Same private key, same encryption, one workspace.
Yes. All content in Calendar is encrypted in your browser using XChaCha20-Poly1305 with a fresh key per item. The UltimaOS server only ever stores ciphertext and public keys — it cannot decrypt your data, no matter who asks.
Calendar uses the same post-quantum stack as every other UltimaOS app: ML-DSA-65 (FIPS 204) for authentication, ML-KEM-768 (FIPS 203) for key encapsulation, XChaCha20-Poly1305 (RFC 8439) for symmetric encryption, HKDF-SHA256 for key derivation, and Argon2id for passphrase hashing.
Yes. Sign in on any device with your passphrase and the same private key is derived locally. All your Calendar content is then decrypted from the encrypted blobs the server returns. Changes sync live across all signed-in devices.
Yes. UltimaOS is built and operated in the European Union by an EU company. The architecture is GDPR-compliant by design — encrypted data, EU-only infrastructure, no US CLOUD Act exposure, no advertising, no third-party trackers. See the GDPR page for the full breakdown.
During early access, UltimaOS is free for individuals and organizations. After early access, pricing will be per-seat with accessible family tiers and per-organization plans for businesses. There is no per-app add-on.
Yes. UltimaOS supports encrypted export of all your content for backup and portability. The export is encrypted to a key you control; you can store it on your own infrastructure or in a personal encrypted backup.
Yes. You can share free/busy, propose-meeting, or full manage access with specific contacts. Each sharing scope is encrypted and revocable at any time.