Privacy

Last updated 14 October 2026

MetaSelf is a personal Android application written for a single user. It is not published on any app store, has no accounts, no analytics, no advertising and no operator. There is no server belonging to this application, and nobody — including its author — can see what you record in it.

What it stores, and where

Everything you log lives on your phone: meals and their nutrition figures, weights, your profile, your goal, your settings, the health record described below, workouts you type in, what you tell the trainer, the note you write about yourself, the trainer's plans and feedback, its weekly letters, your conversation with it, and what it keeps from that conversation about you (every version of it). It is held in the application's own private storage, which no other app can read.

Your OpenAI API key, and your Open Food Facts password if you choose to save one, are stored encrypted against your phone's hardware keystore and are excluded from Android's automatic backup. They are never displayed again after being entered, and never written to any log or export.

What leaves your phone, and when

Seven things. Six are sent only when you do something that requires it; the seventh, the weekly letter and the rewrite that follows it, is sent once a week without a tap for as long as its setting is on.

1. A meal description, and your answers about it, to OpenAI. When you ask for an estimate from words, the text you typed is sent using your own API key. If the app asks you questions about the meal first, each answer — the one you tapped or the words you typed — is sent too, with the questions it answers. Nothing else goes with it — not your weight, age, goal, history or any identifier. Repeating a meal, or typing the numbers yourself, sends nothing at all.
2. One food's name and figures, to OpenAI, when you ask for a review. When you press Review the figures on a food, that one food is sent using your own API key: its name and brand, the figures in the editor, where each came from and how sure an earlier estimate was, what one of it is called, what one of it weighs, and whether the food is new. Nothing else goes with it — no other food, not what or when you ate, not your weight, age, goal or any identifier. Nothing is sent unless you press the button.
3. Your training record, to OpenAI, when you ask the trainer. When you press the button to plan a session, to get feedback on one, to be evaluated and given a plan for the weeks ahead, or to adjust that plan, the request is sent using your own API key and holds: your answers or your words about the session or the plan; the note you wrote about yourself; what the trainer knows about you — the facts it keeps from your conversations (described under the weekly letter), as they stand now; your sessions of the last six weeks (kind, date, minutes, distance, steps, calories, heart rate and heart-rate zones, how each felt and what you wrote about it); for each of six weeks, what you did in and beyond your weekly plan (each planned session's outcome; other sessions by kind with their minutes, distance and minutes in brisk heart-rate zones; steps and distance a day), your food as the days you logged and the average calories and protein a day, with your calorie target, and your average sleep a night, resting heart rate and heart-rate variability, each beside its usual over the four weeks before; one summary line for each of the twelve months before that (sessions, minutes, distance, steps a day, heart rate, how sessions felt, and the change in your weight trend); your smoothed weight trend and how fast it is moving; your goal's direction and rate; your age, sex and height; when you are following a weekly plan, the planned session you are planning or were given feedback on, with its week and how many weeks the plan has; when you ask for an evaluation, the date the plan would start, your last evaluation, the plan that went with it and how many of its sessions you did each week; when you adjust a plan, the plan, the date it started and how many of its sessions you have done; with either, for each planned session, whether it was done, done shorter with your say-so, or not done, and the minutes of the shorter sessions that did not count; and the trainer's last three feedbacks. When you write to the trainer on Your trainer and press Send (or Try again), the request also holds your message and the last 14 days of that conversation, word for word — your messages, its replies, and its feedback and weekly letters of those days, up to the newest 24,000 characters — with your weekly plan, its week and goal when one is running, and the trainer's note on this week. Each message you send is one request; the conversation itself stays on your phone. Never sent: a meal, a food's name, an amount or a time of eating, a single night's sleep or a single day's heart rate, sleep stages, oxygen, breathing rate, individual readings, a single weigh-in, a target weight, your name, or which app or device recorded a session. The same list is shown on screen beside the button. Settings → Test the trainer's instructions sends the same request, when you press Send, under the app's own instructions or ones you load from a file, without asking for the reply's usual shape; it stores nothing, and counts as one of the day's AI requests.
4. Your week in figures, to OpenAI, for the weekly letter — once a week, without a tap. While the Weekly letter setting is on (it is on unless you switch it off, in Settings → AI), the application asks for a short letter about your week once a week, on Sunday evening at the hour you choose, without your pressing anything; a week with nothing logged sends nothing. The request uses your own API key and holds: the week's food only as averages a day of calories, protein, carbohydrate and fat, and the number of days you logged — never a meal, a food's name, an amount or a time of eating; the change in your smoothed weight trend over the week (never a single weigh-in); the week's sessions (kind, minutes, distance, calories, heart rate and heart-rate zones, steps — never what you wrote about them), how many of them felt easy, right or hard, and your steps and active calories a day; what you did in and beyond the weekly plan, and your average sleep a night, resting heart rate and heart-rate variability, each beside its usual over the four weeks before; the weekly plan's week, when one is running; the note you wrote about yourself; what the trainer knows about you; your goal's direction and rate; your age, sex and height; today's calorie target; last week's letter's "for next week" line; and the same figures for each of the four weeks before. If you allow Health Connect's background access, the application first copies your band's data, as it does when you open it. Never sent: a meal or anything about one, a single night's sleep or a single day's heart rate, sleep stages, oxygen, breathing rate, individual readings, a single weigh-in, your name, or which app or device recorded a session. The letter is kept on your phone. Write it now, on the Weekly letters screen, sends the same request when you press it.
   
   After the Sunday letter, a second request rewrites what the trainer knows about you (What I know about you, on the Trainer page), also without your pressing anything. It uses your own API key and holds: that list of facts as it stands, with the ones you changed or removed marked so; the note you wrote about yourself; and your conversation with the trainer since the last rewrite, word for word — your messages, its replies, and its feedback and weekly letters of that time, up to the newest 48,000 characters. Nothing else from your record goes with it. A week in which you wrote nothing to the trainer sends no rewrite. Every version of the list is kept on your phone, so a rewrite can be undone.
5. A barcode number, to Open Food Facts. Only the number. The camera is used for nothing but reading barcodes; the picture is read on the phone and never stored or sent. A product you have scanned before is answered from your own phone and sends nothing.
6. A product you choose to contribute, to Open Food Facts. Only if you have entered an account, and only when you press the button, one product at a time. What is sent is the barcode, name, brand, serving size and the figures on the label — plus your Open Food Facts username, because that database credits contributions. Nothing about you goes with it: not your weight, your history, or what or when you ate.
7. Backup files, to your own Google Drive, if you turn that on. The application requests the drive.file scope, which grants access only to files the application itself creates. It cannot see, list, open or modify anything else in your Drive. The daily file is the same export you can save by hand — which includes your health record, workouts, sleep, the trainer's plans and feedback, your conversation with it, what it knows about you and your note about yourself — and your API key is deliberately not in it. The detailed health readings, too many for a daily file, go as one compressed file per month.

That is the complete list. There is no analytics, no crash reporting, no advertising identifier, no tracking of any kind, and no other network destination.

Health and fitness data

If you allow it, the application reads from Android's Health Connect: steps, distance, active and total calories burned, exercise sessions, heart rate, resting heart rate, heart-rate variability, oxygen saturation, respiratory rate, sleep, weight and body fat, including history older than Health Connect's usual 30 days, and — only if you allow it, from the Weekly letter setting — while the application is not open, so Sunday's letter includes the sessions of that day. It keeps its own copy on your phone, noting which app each figure came from, and uses it to work out whether you have moved more than usual, to show the Movement screen, and to answer the trainer.

A workout file you share into the application from another app is read on the phone and sends nothing.

Your data is yours

You can export everything to a single readable file at any time, and keep it wherever you like. You can have a copy written automatically into a folder of your choosing.

To delete everything, uninstall the application. Android removes its private storage with it. Files it wrote to your own Google Drive or to a folder you chose are yours and stay where they are until you delete them; nothing is held anywhere else, because there is nowhere else.

Children

This application is not intended for, or directed at, children.

Contact

This is a personal project. Questions or concerns can be raised as an issue on GitHub.