# FAQ

Short answers, with a link to the long one.

### What does it cost?

Nothing. openGym is open source under the AGPL: no subscription, no paid tier, no ads. If you'd like
to support it anyway, there's [Buy Me a Coffee](https://buymeacoffee.com/duartesantos).

### Do I need my own server?

No, there are three ways to use it:

- **Try it:** the [online demo](https://opengym.duarte-santos.ch/demo/) runs entirely in your
  browser with example data.
- **Phone only:** the Android app needs no server and no account; everything stays on the phone.
  See [MOBILE.md](MOBILE.md).
- **Your own instance:** `docker compose up` on any machine with Docker gives you sync between
  devices and profiles for friends and family. See [SELF_HOSTING.md](SELF_HOSTING.md).

### Is there an iPhone app?

Not in the App Store, and Apple doesn't allow installing apps from anywhere else. On an iPhone you can
self-host and add openGym to your home screen from Safari (it's a full PWA that works offline), or
build the native app onto your own phone with Xcode. Both are described in [MOBILE.md](MOBILE.md).
An App Store build is on the [roadmap](../ROADMAP.md).

### Why isn't it on the Play Store?

That's deliberate. The APK is signed, published with a `.sha256` next to every release, and the app
checks for updates itself. Get it from the
[latest release](https://github.com/DuarteSantos8/openGym/releases/latest).

### Where is my data?

On a self-hosted instance, in the `./data` folder next to `docker-compose.yml`: one JSON file per
profile plus the account list. Back up that folder and you've backed up everything. In the phone app
it's in the app's private storage. In guest mode it's only in that browser. You can export
everything as one file at any time under **Settings → Data**.

### Does the app send anything anywhere?

Your instance has no telemetry and phones home to nobody. On first start it downloads the exercise
images and animations from the upstream dataset, once. The AI coach, if an admin turns it on, sends
the training data it needs to the provider you configured; [AI_COACH.md](AI_COACH.md) lists exactly
what. Push notifications go through your browser's push service, as all web push does.

### Was openGym written with AI?

It's developed with [Claude Code](https://claude.com/claude-code), Anthropic's coding agent, and a
large share of the code, tests and docs is drafted that way. The maintainer decides what goes in,
reviews it, and tests every release on a staging instance and on real phones. The longer answer is in
the [README](../README.md#how-opengym-is-built).

### Does the app itself use AI?

Only if you turn it on. The default install calls no AI service. Two optional pieces exist: the
[AI coach](AI_COACH.md) (off until an admin enables it, runs with your own provider key, every
change needs your approval) and the [MCP server](../mcp/README.md), which lets an AI client on your
computer read your history. Neither is needed for anything else in the app.

### My passkey sign-in doesn't work.

Almost always one of two things:

1. You're opening it over plain `http://` on a LAN address. Passkeys only work over HTTPS (or on
   `localhost`). Use guest mode, turn on password sign-in, or put it behind HTTPS.
2. `RP_ID` and `ORIGIN` in `.env` don't match the address in your browser exactly.

[SELF_HOSTING.md](SELF_HOSTING.md#2-understand-the-passkey-requirement-important) explains both, and
its troubleshooting section covers the rarer cases.

### Can I use a password instead of a passkey?

Yes, if the instance allows it: set `PASSWORD_LOGIN=1`. It's off by default. See
[password sign-in](SELF_HOSTING.md#password-sign-in-optional).

### Can several people use one instance?

Yes. Everyone creates their own profile and sees only their own data. You can make signup
invite-only and give yourself an admin dashboard; see
[multiple users](SELF_HOSTING.md#4-multiple-users).

### How do I update?

`git pull && docker compose pull && docker compose up -d`. Your data is untouched. See
[updating](SELF_HOSTING.md#8-updating).

### I'm moving from another app. Can I bring my history?

FitNotes, Strong and Hevy work out of the box, Apple Health for body weight, and any CSV with a date,
an exercise and something measured. See [DATA_IMPORTS.md](DATA_IMPORTS.md).

### Can I reuse the exercise images in my own project?

Not on openGym's say-so. The images and animations aren't covered by openGym's license and their
ownership is disputed; openGym only downloads them for your instance. Details in
[NOTICE.md](../NOTICE.md).

### Where do I ask something that isn't here?

The [Discord](https://discord.gg/e62jY6fwVb) for a quick answer,
[Discussions](https://github.com/DuarteSantos8/openGym/discussions) if the next person should be
able to find it, [Issues](https://github.com/DuarteSantos8/openGym/issues) for a bug.