TellFin Privacy Policy
Last updated: 20 October 2026
TellFin is a fishing forecast app: it shows how likely fish are to bite, based on pressure, geomagnetic activity, the moon and wind, and explains why. This policy explains what data the app uses, where it goes and how to delete it. In short: your fishing spots stay on your phone unless you turn on the cloud backup yourself, and we do not sell data, show ads or track you.
Who is responsible
TellFin is developed by Nelin Vitali. Contact for any privacy question or request: tellfin.support@gmail.com.
What stays on your phone
Your places with exact coordinates, your fishing journal (trips, catch, notes, recorded conditions), your chosen fish species and settings are stored only on your device. Uninstalling the app deletes them.
What is sent to our forecast server
To calculate the forecast, the app sends the place's coordinates rounded to 0.01° (about 1 km) — never the exact spot. The server does not create accounts and does not store which device asked for which place. Like any web service, our hosting provider (Railway, servers in the EU) keeps short technical logs of requests (IP address, time, rounded coordinates) for security and troubleshooting.
The server gets weather from Open-Meteo and geomagnetic data from NOAA using rounded grid coordinates only; no personal data is passed to them.
Optional: cloud backup of places and journal
Off by default. If you turn on “Back up places and journal”, the app creates an anonymous account (no email or password) with Supabase (database in Frankfurt, EU) and stores there your places with exact coordinates, your journal and your app settings (chosen fish species, selected place, which alerts are on, pressure unit and app language) — so that after signing in on a new phone everything is as before. Only you can access them. Turning the backup off deletes this copy from the cloud.
Optional: signing in with Google
You can use TellFin without an account. If you tap “Sign in with Google” to keep your places and journal and restore them on a new phone, we receive from Google your email address and Google account ID. They are stored with Supabase and used only to sign you in. Signing in turns on the cloud backup described above.
Deleting your account: in the app, open Places → Account → “Delete account”. This deletes your account and everything stored in the cloud; data on your phone stays. You can also ask us by email at tellfin.support@gmail.com.
How TellFin uses Google user data
When you sign in with Google, TellFin requests only your basic profile: email address and Google account ID (the standard “email” and “profile” sign-in permissions). TellFin does not access your Gmail, contacts, calendar, Drive, photos or any other Google data.
- Use: only to identify your account so your places and journal can be backed up and restored on another phone.
- Sharing: not shared with anyone and not sold. It is stored with our database provider Supabase only to run the sign-in.
- No advertising and no AI training: Google user data is never used for ads and never used to develop, improve or train AI or machine-learning models.
- Deletion: “Delete account” in the app removes it immediately, or write to tellfin.support@gmail.com.
TellFin's use of information received from Google APIs adheres to the Google API Services User Data Policy, including the Limited Use requirements.
Optional: notifications
Off by default. If you turn on alerts (good bite tomorrow, magnetic storm, sharp pressure change), our server stores: this device's notification token, app language, pressure unit, which alerts you chose, and your selected place rounded to about 1 km. Alerts are delivered through Firebase Cloud Messaging (Google). Turning all alerts off deletes this record; an invalid token is deleted automatically.
Crash reports
If the app crashes or hits an error, it sends a crash report to Firebase Crashlytics (Google): what went wrong in the code, the app version, phone model and Android/iOS version, and a random installation ID. Crash reports contain no location, places, journal or account data. They help us fix bugs.
Location permission
The app asks for location only when you tap “Use my location”, to add your current position as a place. Location is read by the phone's own location service; the app does not track you in the background.
Map
When you pick a place on the map, map images are loaded from OpenStreetMap servers, which receive your IP address and the map area being viewed, as with any web map.
What we do not do
- No advertising and no advertising IDs.
- No analytics or tracking SDKs (crash reports are used only to fix errors).
- No selling or sharing of personal data.
Service providers
| Provider | What for | Data |
|---|---|---|
| Railway (EU) | Forecast server hosting | Rounded coordinates, technical logs |
| Supabase (Frankfurt, EU) | Optional backup; notification subscriptions | See the sections above |
| Google Sign-In | Optional sign-in | Email address, Google account ID |
| Google Firebase Cloud Messaging | Delivering notifications | Notification token, message text |
| Google Firebase Crashlytics | Crash reports | Error details, app version, phone model, random installation ID |
| OpenStreetMap | Map images | IP address, map area |
How long we keep data
Cloud backup and notification subscriptions are kept until you turn them off or ask us to delete them. Technical server logs are kept for a short time by the hosting provider; crash reports are kept by Crashlytics for up to 90 days.
Your rights
You can delete your cloud data at any time in the app (turn off backup or notifications). You can also ask us to access, correct or delete your data, or object to its processing, by writing to tellfin.support@gmail.com. If you are in the EU/EEA or the UK, you may also complain to your data protection authority.
Children
TellFin is not directed at children under 13 and does not knowingly collect their data.
Changes
We will update this page if the app starts handling data differently, and change the date at the top.