Your health logs
Meals, water, workouts, weigh-ins, sleep, supplements, trackers and your day reviews, mood included.
Security
Private by architecture.
A health coach only works if you can tell it everything, so this page says plainly what stays on your device, what leaves it and why, and how everything that moves is protected. Every claim here describes how Kata is actually built, not how we hope it behaves.
On your device
What lives on your device.
Your personal content is written to your device, in the app's own local storage. Nothing here flows through a Kata content database, because there is none. In the web app and the Android app, one restore snapshot also travels, and it leaves your device already sealed: it has its own section below.
Your conversations
Every chat with Kata, and the memory of locked-in facts it builds with you.
Your photos
Progress and food photos live in the device's local database, never in ours. The sealed snapshot of the web app and the Android app leaves them out entirely; on iPhone and Android they stay in the backup files your phone keeps.
The especially private
Health concerns, medication names, your cycle log and Sensei letters are kept on your device like everything else, and treated with extra care on top.
Your seasons and weeks
Closed weeks, kept seasons and every insight derived from your data are computed and stored locally.
Yours to see and delete
The app's What Kata knows page lists every fact it holds, with its source, and lets you delete any of it.
Across the wire
What leaves, and why.
Kata's servers are deliberately boring: your account and plan, consent records, notification settings and the push token, usage counters and pseudonymous persona traits, the Duo and group dots and secure shares you create, a company membership and its history if an employer covers you, a gift you give or receive (its card, the names and note on it, kept until 90 days after it is claimed), and, for the web app and the Android app, one sealed restore snapshot. Never your logs, chats, photos or Kata's memory of you. These are the moments data crosses, always over an encrypted connection.
When you talk to Kata
Your message and just enough context, including the Apple Health, Health Connect or WHOOP values a question needs, travel to the AI, answer that one request and come back. Kata's servers keep no copy: what remains with us is a content-free row of token counts and model tier. The AI provider, Anthropic, never trains on it and deletes it within 30 days.
Your account
An email address and a sign-in, your plan and the record of what you agreed to: enough for your account to exist and to be recovered. Delete your account and every operational row about you goes with it, apart from billing records, the record of what you agreed to and one-way fingerprints that keep free offers to one per person.
A daily heartbeat
Once a day the app reports that your platform was active, and sends three plain facts: platform, app version and a country code derived on our server. No health data, no behavior, nothing about your day.
Shares, letters and the snapshot
A secured share and the existence of a letter cross only when you ask for them. In the web app the restore snapshot runs on its own: after you change something, at most every quarter of an hour, and every six hours when nothing has changed, so a new browser can bring your history back with your recovery code. The Android app works the same way. It is encrypted on your device before it goes, so what crosses is ciphertext.
When Kata speaks
On the paid plans, the text of a read-aloud, a voice note or a spoken Talk reply is sent to a voice provider to be turned into audio. It is transient, and nothing is recorded or stored.
Notifications
Turn them on and your device's push token and your choices are kept with your account: categories, quiet hours, how often, your language and time zone, so a reminder lands at the right local hour. A short ledger of what was sent is kept for 21 days, so nothing arrives twice.
The measures
How the moving parts are protected.
Where data does move, the protection is structural: encryption and ownership rules that are part of the code, not a policy promise.
Encrypted in transit
Every connection between the app, our servers and the AI runs over TLS. There is no unencrypted path.
Sealed connection tokens
Your WHOOP sign-in never lands in a server token database. On your phone the token is handed back as a sealed, encrypted blob only our server functions can open; on the web it lives in an httpOnly cookie.
The encrypted share
When you send a doctor a data share, the summary is encrypted on your device with AES-256-GCM. The key travels only in the link itself and is never sent to or stored on our servers: we hold ciphertext, a salted hash of the recipient's email, and an expiry.
The sealed account snapshot
The restore snapshot of the web app and the Android app is encrypted on your device with AES-256-GCM before it is uploaded. The key is a random 256-bit value that lives in your device's secure storage and in your recovery code, and it is never sent to us: not in the row, not in a column, not in a header. What we store is the sealed envelope alone, with no key, no key id and no check value beside it, so there is nothing here to read and nothing to test a guess against.
Owner-only tables
Every operational table is guarded by row-level security. The one row that holds account content, the sealed restore snapshot, is locked to your own signed-in account: no other account can reach it, and nobody can read it, us included.
Backups
Your backup, in your hands.
Backups exist so a lost phone never means a lost history, and they follow the same ownership rules as everything else.
- The iPhone appKata writes a plain backup file to the app's own Documents folder, photos included and Apple Health values left out, since Apple Health keeps those itself. Your iPhone's own iCloud backup carries that file like any other app data, protected the way Apple protects that backup, and you can export a copy any time. None of it reaches our servers, and nothing restores itself at sign-in.
- The Android appKata writes backup files to its own private storage on your phone, once a week unless you choose otherwise, photos included and Health Connect values left out, and your own Google backup can carry them. The Android app also keeps one sealed restore snapshot with us, exactly like the web app below, and its key waits with your Google account too, so a new Android phone set up from that account can open the snapshot without the recovery code.
- The web appA browser has no private per-user cloud to lean on, so Kata keeps one restore snapshot per account in our database: one row, locked to your account by row-level security, no photos, refreshed at most every quarter of an hour after a change and every six hours otherwise. It is encrypted on your device before it leaves, under a key we never receive, so the row holds ciphertext we have no technical means to read. Your recovery code is what opens it on a new device, and if the seal cannot be made, nothing is uploaded at all.
- Export my dataIndependent of all three, one complete file of everything, prepared on your device. Keep it wherever you like, import it anywhere.
FAQ
Fair questions, straight answers.
Where does my data actually live?
On your device. Logs, chat history, Kata's memory of you, photos and integration tokens are written to your device, not into a content database of ours. Two things travel: your message and the context it needs go to the AI to generate a reply, where Kata's servers keep no copy and the AI provider deletes it within 30 days without training on it; and, in the web app and the Android app, one restore snapshot of your account, encrypted on your device with a key we never receive, so what we hold is ciphertext we cannot open. That is how Kata is built, not just a promise. Details in the data & privacy model.
What does the server see?
- Your account basics: email and sign-in timestamps.
- How often the app is opened and when it was last active.
- Aggregate AI usage numbers for fair use: never what was said.
- A pseudonymous picture of you the app computes on your device, tied to your account: an archetype word and coarse traits like activity level, sleep pattern or phase. Never names, numbers or content.
- Your invite status, your plan and its subscription state.
- Your push token and notification settings: categories, quiet hours, how often, language and time zone, plus a 21-day ledger of what was sent.
- The record of the Terms and Privacy versions you accepted.
- If you use them: the daily yes-or-no dot of a Duo or group, the sealed secure shares you create, and your membership and its history (when you were invited, joined or left) when a company covers your plan.
- If you give or receive a gift: its code, length and card, the names and note written on it, how it arrives (the recipient's email or a postal address), and who claimed it and when. The names, the note and the addresses go 90 days after the gift is claimed.
- In the web app and the Android app, one restore snapshot of your account: a sealed blob we hold no key for.
- Standard technical hosting logs (IP, request time) at Vercel.
Never readable to us: your chats, your logs, Kata’s memory of you, your decisions. Your photos are never stored on our servers. What the restore snapshot carries is ciphertext, sealed on your device with a key we never receive, so we can hold it but not open it. We never build an advertising profile from any of this and never sell it. The marketing website does use basic, aggregate visitor analytics you can decline, and it never touches any of this.
Can I export or wipe my data?
Yes. The app has a full JSON export, worth keeping as your own backup, and a wipe that clears everything from the device. Deleting your account removes the email record and, for the web app and the Android app, the encrypted snapshot with it. On the web and on Android, keep your recovery code: a snapshot opens only with your device key or that code, and not even we can open it for you.
What happens when I talk to Kata?
Your message, plus the minimum context needed to answer it, including the Apple Health, Health Connect or WHOOP values the question needs, is sent encrypted to our AI provider, Anthropic, which answers it, never trains on it and deletes it within 30 days. Kata's servers keep no copy. Your voice is turned into text by Apple's speech recognition on iPhone, your phone's speech recognizer on Android or your browser's on the web before anything reaches us, and photos go to the AI only when you send them.
Does Kata learn from my data?
Yes, in a way we are proud of. Kata learns from abstract patterns, things like “morning trainers with a steady sleep rhythm stick to their plans”, so the product gets better for everyone. What it learns from is a coarse, pseudonymous sketch (an archetype and traits like activity level or sleep pattern, tied to your account but never to your content), computed on your device. Never your chats, never your logs, never your photos, never anything that tells your story. Those stay with you, full stop.
What happens to my data if I delete my account?
Deleting your account removes your email and sign-in record from our systems, with everything tied to them: your plan, notification settings, Duo and group dots, shares and, for the web app and the Android app, the encrypted snapshot. What stays: billing records for their statutory period, the record of what you agreed to for ten years, and, for 24 months, one-way fingerprints of your email and sign-in, so that the free month and invite rewards go to each person once. Nothing readable about your health was ever there. Wiping the app clears your local data completely and instantly. Export first if you want a backup.
How do the physique photos stay private?
Progress photos are written to your device, like everything else personal. They are never stored on our servers: the sealed snapshot of the web app and the Android app leaves them out entirely, and they serve nothing but your own before/after view. On iPhone they are part of the backup file your phone's own iCloud backup carries, and on Android they are part of the backup files your Google backup can carry. If you ask Kata to analyze one, the image goes to the AI provider for that answer only: Kata's servers keep no copy, and the provider deletes it within 30 days.
Which AI provider does Kata use, and how long is a message kept?
Anthropic runs the coach: your message and the context it needs go there to make the reply. Anthropic does not use it for training and deletes it within 30 days, and Kata's own servers keep no copy of the conversation. ElevenLabs turns what Kata says out loud into audio in a Kata voice, Mégane's or another you choose, on Kata Plus and Kata Unlimited, and receives only the text of that reply.
How do I delete my account?
In the app: open Profile, scroll to the bottom, choose Delete account and type DELETE to confirm. Your account and its server records go at once, apart from billing records, the record of what you agreed to and one-way fingerprints that keep free offers to one per person (see Delete your account), and the Kata data on that device is wiped with it. Export first if you want to keep a copy.