Privacy Policy
Last updated 25 August 2026 · BUILDeutsch, published by Mango Medicine LLC
The short version.
There is no account, so we do not know who you are. Your progress, your settings and your saved words stay on your phone.
Two things leave your device: sentences you type into the Builder, which go to our server and on to Anthropic and OpenAI so they can be analysed and read aloud; and a rounded location — about 11 km of precision — if you allow it, purely to show the local weather.
There are no adverts, no analytics and no trackers of any kind.
1. Who we are
BUILDeutsch is a German-learning app published by Mango Medicine LLC. You can reach us at support@buildeutsch.com about anything in this policy.
2. There is no account
The app has no sign-up, no login and no user profile. We do not ask for your name, your email address or your date of birth, and we have no way to connect any request to a particular person.
3. What stays on your phone
All of the following is stored locally on your device and is never transmitted to us:
- Your learning progress and review schedule
- Words and phrases you bookmark
- Your settings — level, daily goal, theme, voice, haptics
- Your answers to the onboarding questions
Deleting the app removes all of it. Settings also contains a Reset all progress option that erases it without uninstalling.
4. What leaves your phone, and where it goes
| What | When | Where it goes |
|---|---|---|
| The sentence you type or dictate | When you ask the Builder to analyse it | Our server, then Anthropic (Claude) to be parsed and explained |
| A recording of your voice | Only when you use dictation | Our server, then OpenAI to be transcribed |
| German text to be spoken | When you press play on a sentence | Our server, then OpenAI to be turned into audio |
| Approximate location, rounded to ~11 km | Only if you grant location permission | Our server, then Open-Meteo for the weather |
Our server is operated by us on Fly.io and runs in Frankfurt, Germany.
About the sentences you type
Our server does not log or store the text of your sentences. It passes them to Anthropic, returns the analysis to your phone, and keeps nothing. Anthropic and OpenAI process the text under their own terms and their own retention periods, which we do not control.
Because that text leaves your device, please do not type anything you would not want a third party to process. The Builder shows this warning on screen for the same reason: never enter real patient names or identifiable health information — use fictional or de-identified information only.
About location
Location is optional and the app works fully without it. If you grant permission, the app requests a low accuracy position and then rounds it to one decimal place — roughly 11 km — before it is sent anywhere. That is enough for a weather reading and not enough to identify a street, a building or a person. We do not store it; the weather result is cached against the rounded coordinate for fifteen minutes and then discarded. You can revoke the permission at any time in your phone's settings.
5. What our server records
Like any web server, ours sees the IP address a request arrives from. We use it for one purpose: rate limiting, so that nobody can run up unbounded costs against the service. When a request is refused for exceeding a limit, the IP address is written to a transient log. We do not build profiles from it, we do not connect it to anything else, and we do not retain it beyond our hosting provider's ordinary log rotation.
6. What we do not do
- No advertising, and no advertising identifiers
- No analytics or usage tracking of any kind
- No third-party trackers, pixels or SDKs for measurement
- No selling or sharing of personal information — we have none to sell
- No cross-app or cross-site tracking
7. Children
BUILDeutsch is not directed at children under 13, and we do not knowingly collect personal information from them. Since there is no account, we hold no information that would identify a child. If you believe a child has submitted personal information through the app, write to us and we will help.
8. Your rights
Depending on where you live — including under the GDPR in the EU and UK, and the CCPA in California — you have rights to access, correct, delete and port your personal information, and to object to its processing.
In practice these are simple here: the data we could return to you is the data already on your phone. Deleting the app, or using Reset all progress, deletes it. For anything else, write to support@buildeutsch.com and we will respond within 30 days. You may also complain to your local data protection authority.
9. Processors we rely on
- Anthropic — analyses the sentences you submit
- OpenAI — speech recognition and speech synthesis
- Open-Meteo — weather for a rounded coordinate
- Deutsche Welle — public news headlines; no data about you is sent
- Fly.io — hosts our server
- Apple and Google — distribute the app and handle crash reports at the operating-system level under their own policies
10. Changes
If this policy changes we will update the date at the top of this page. If a change is significant — new data leaving your device, or a new processor — we will say so in the app before it takes effect.