Legal

Privacy Policy

Effective date: 1 April 2025 · Last updated: 1 April 2025

The short version

Cossi does not collect, transmit, or store any of your personal data on any server we operate. Everything — your calendar, contacts, email credentials, AI conversations, vault contents, and seed phrase — stays on your device. We have no access to it.

1. Who we are

Cossi is a personal productivity application developed and published by SI Analytics Ltd ("we", "us", "our"). We are registered in England and Wales. If you have questions about this policy, contact us at customer_services@sianalytics.tech.

2. Information we collect

We collect no personal information. Cossi is a local-first application. There are no user accounts on our servers, no analytics SDKs, and no background data transmission of any kind.

What stays on your device

Calendar data — Events you create or sync via CalDAV are stored in a local SQLite database on your device only.
Contacts and relationship data — All contact information, relationship health scores, voice notes, and interaction history are stored locally in SQLite.
Email credentials and messages — Your SMTP/IMAP credentials are encrypted with AES-256-GCM and stored in the device's secure enclave. Email content is fetched directly from your mail server and never routed through our infrastructure.
Vault contents — Notes, documents, and context stored in the encrypted vault remain on-device and are encrypted with AES-256-GCM using a key derived from your seed phrase.
AI conversations — Prompts and responses are processed entirely by the on-device language model (via llama.rn). Nothing is sent to any AI provider or external API.
Authentication keys — Your ML-DSA-65 (Dilithium) private key and BIP-39 seed phrase are generated and stored exclusively on your device. We never see them.
Tasks and todos — All task data is stored locally in SQLite.

What we do not collect

Crash reports or diagnostics (no Sentry, Firebase, or equivalent)
Analytics or usage telemetry (no Mixpanel, Amplitude, or equivalent)
Device identifiers, IP addresses, or location data
Any content you type, record, or store in the app

3. Apple App Store and TestFlight

When you download Cossi from the Apple App Store or access it via TestFlight, Apple collects certain information as part of its standard platform operation (e.g. download records, crash logs if you have opted into sharing these with developers). This collection is governed by Apple's Privacy Policy, not ours.

Crash reporting: If you opt in to sharing crash data with developers in your iOS settings, Apple may forward crash reports to us. These reports contain technical stack trace information only — no personal data, no vault contents, no message content.

4. Third-party services

Cossi connects to services that you configure — your calendar server, your email provider, and optionally your cryptocurrency node. These connections are made directly from your device to those services. We are not party to those connections and do not intermediary, log, or inspect them.

The following optional integrations may involve third-party services:

CalDAV sync — connects to your calendar provider (e.g. Google Calendar, iCloud) directly from your device.
SMTP/IMAP email — connects directly to your mail server; your credentials are not shared with us.
Wallet / on-chain balance — public RPC endpoints (Ethereum, Polygon, Base, BNB Chain) are queried directly from your device using your public address only.
CoinGecko — price data is fetched from CoinGecko's public API. No account identifier is sent.

5. Data security

Cossi's security architecture is designed so that a breach of our infrastructure — should one ever occur — would expose no user data, because we hold none. Nonetheless:

The vault is encrypted with AES-256-GCM; decryption requires your seed-phrase-derived key.
Authentication uses ML-DSA-65 (CRYSTALS-Dilithium), a NIST-standardised post-quantum signature scheme. Your private key never leaves your device.
Email passwords are Fernet-encrypted before being written to local storage.
SQLite databases are stored in the app's private sandbox, inaccessible to other apps.

6. Your seed phrase

Your 24-word BIP-39 seed phrase is the master key to your account and encrypted vault. We do not store it, cannot recover it, and have no mechanism to reset it. If you lose your seed phrase, your vault contents cannot be recovered. Store it securely offline.

7. Children's privacy

Cossi is not directed at children under 13. We do not knowingly collect any information from children. If you believe a child has provided information through our app, please contact us and we will take appropriate steps.

8. Changes to this policy

If we make material changes to this policy, we will update the effective date above and notify users via an in-app notice on the next app open. Continued use of Cossi after the effective date constitutes acceptance of the updated policy.

9. Your rights

Because we hold no personal data about you, most data subject rights (access, erasure, portability) are exercised directly on your device. If you have questions or concerns, or wish to exercise any rights under applicable data protection law, contact us at the address below.

10. Contact

For privacy questions or data subject requests:

SI Analytics Ltd
Email: customer_services@sianalytics.tech

Questions about privacy?

We're straightforward to reach. If something in this policy is unclear, email us and we'll respond within 2 business days.

customer_services@sianalytics.tech