Privacy Policy

Last updated: July 2026

This policy explains what VYTLAÜ collects, where it's stored, and what stays on your device. We've tried to write it the way we'd want to read it — plainly, and in the order you'd actually ask the questions.

The short version

Your health data — weight, sleep, mood, journal entries, medical ID, and everything else you log day to day — stays on your device. It is never sent to our servers. Only what's needed for the social features (your username, display name, avatar, friends, and challenges) lives on our servers, and you can delete that at any time.

What stays on your device Local only

The following is stored using your browser's local storage, on your device only. We have no access to it, cannot see it, and it is never transmitted to any server:

Weight, steps, heart rate, blood pressure, distance, and calorie logs
Sleep, water intake, mood, and stress logs
Body measurements and progress photos
Journal entries and habit tracking
Fasting logs and workout history
Your Medical ID (blood type, allergies, medications, conditions, emergency contact)
App preferences (units, dark mode, notification settings)

Because this data never leaves your device, it also isn't backed up by us. If you clear your browser data, uninstall the app, or switch devices without exporting first, it's gone. Use Export my data in your Profile settings to download a copy anytime — and Import data to restore it on a new device.

What we store on our servers Server-side

If you create an account to use friends and challenges, we store:

Your username, display name, and avatar (an emoji, a small photo, or your initials)
Your password, one-way hashed — we cannot see or recover your actual password
A one-way hashed recovery code, used only to verify a password reset
Friendships and friend requests
Challenges you've created or joined, and your progress within them
Badges earned from completed challenges

That's the complete list. We don't store your weight, your journal, your medical information, or any other health data on our servers — those never reach us in the first place.

The AI trainer

If you use the AI trainer chat, your messages are sent to Anthropic's Claude API to generate a response. We don't store your chat history on our servers — it's kept in your browser's local storage, same as your other health data. Anthropic's own privacy practices govern how they handle messages sent to their API while generating a response; we send only what's needed to answer your question.

Cookies and tracking

VYTLAÜ doesn't use cookies, third-party trackers, or advertising identifiers. We don't currently run analytics on your usage of the app. Your login session is kept in local storage on your device, not in a cookie.

Your rights

You can, at any time and without contacting us:

Export everything stored locally on your device, from Profile settings
Delete your account from Profile settings, which permanently removes your username, friendships, challenges, and badges from our servers
Clear your local data by clearing your browser's site data for vytlau.com, or uninstalling the app

Account deletion is immediate and cannot be undone. If a challenge you created still has other participants, we keep the challenge running for them rather than deleting it out from under the group — but it's no longer associated with your account in any way.

Who else sees your data

We don't sell your data, and we don't share it with advertisers. The only third parties involved are:

Our hosting provider, which runs the server your account data lives on
Anthropic, only for messages you send to the AI trainer chat, and only for as long as it takes to generate a reply

Children

VYTLAÜ is intended for users aged 16 and older. We don't knowingly collect data from anyone younger.

Changes to this policy

If this policy changes in a way that affects how your data is handled, we'll update the date at the top of this page. Meaningful changes will be communicated in-app.

Contact

Questions about this policy or your data can be sent to hello@vytlau.com.