Your Data Stays on Your Phone. Period.
In a world where apps harvest your data, VivaLyn Sathi takes a fundamentally different approach. All your personal data lives on your device — conversations, diary entries, tasks, expenses, health data, and memories never leave your phone. No cloud database. No server-side profiles. No data mining.
Everything Lives on Your Device
VivaLyn Sathi uses a local-first architecture powered by Realm, an encrypted on-device database. Every piece of data you create is stored directly on your phone.
Conversations & Messages
Stored locally with session tracking. Raw conversation history is never sent to any server.
Diary Entries
AI-generated daily journals based on your conversations, kept entirely on-device.
Tasks & Reminders
Your planner, to-dos, and schedules stay on your phone.
Expense Tracking
Financial data including amounts, categories, and budgets — all local.
Wellness & Mood Data
Emotional signals, sleep, water intake, exercise — private health data that never leaves your device.
Medication Tracking
Dosage schedules, stock levels, and adherence logs — sensitive health information kept strictly on-device.
Memory Summaries
AI-compressed conversation context stored locally for personalised interactions.
How AI Works Without Cloud Data
If data stays on the phone, how does the AI work? VivaLyn Sathi uses a stateless proxy that processes and forgets — immediately.
On-Device Prompt Building
The app constructs a structured prompt locally, pulling context from your on-device database. It uses compressed memory summaries — not raw conversations — to give the AI context.
Minimal Data Transmission
Only the current message and compressed summaries are sent to the AI service. No personal identifiers, no conversation history dumps, no raw data.
Process & Forget
A lightweight FastAPI proxy handles the AI request and returns the response. The proxy stores nothing — zero retention, zero logging of user content.
Response Stored Locally
The AI response comes back to your phone and is stored in your local encrypted database. The proxy retains nothing.
Privacy by Architecture, Not by Promise
Encrypted On-Device Database
All data is stored in an encrypted Realm database. Even if someone gains physical access to your device, the data is protected by encryption.
Voice Profile Security
Your voice identity is stored as a mathematical embedding vector, never as raw audio. Voice recordings are processed and immediately discarded. You can delete it anytime.
Token Budget Enforcement
Strict token budgets — ~200 tokens for short-term, ~500 for long-term summaries. Even the compressed context sent to AI is minimal with no unnecessary personal details.
No Tracking, No Analytics, No Ads
No analytics SDK, no ad networks, no tracking pixels. Your usage patterns are not monitored, collected, or sold. The app serves you, not advertisers.
Offline Capability
Core features work without internet. Your data is always accessible because it lives on your device. On-device speech recognition works offline too.
Consent-Based Design
Voice consent and memory consent are explicit opt-in choices. Cloud backup is disabled by default. You decide what the app can do — always.
An AI That Respects Your Privacy
Download VivaLyn Sathi and experience an AI companion where your data stays yours — on your phone, under your control, always.