Privacy Policy
Last updated: 20 August 2026
Grindster is a small, personal learning app. This page explains what data it collects and how that data is used - there isn't much of it.
What we collect
- An anonymous session identifier. The first time you open the app, it generates a random identifier - not your name, email, or any kind of account - and stores it in a browser cookie so the app can remember your progress between visits.
- Lesson progress. Tied to that anonymous identifier: which lessons and questions you've seen, whether you answered correctly, and when you last answered. This is kept in a persistent database and is retained across app updates and server restarts.
- Decks you create. If you build your own quiz deck in the app, its title and every question in it are stored the same way, tied to your anonymous identifier. A deck you make is private to your session - there's no way for anyone else, including us, to browse, play, or share it.
We do not collect your name, email address, location, or any other personally identifying information. There are no user accounts or logins. The app shows no advertising and includes no third-party analytics or tracking scripts.
Whack-a-Mole minigame
Scores in the Whack-a-Mole minigame are never saved anywhere. They exist only in your browser tab for that one round and disappear as soon as you leave the page.
Creating, exporting and importing decks
You can write your own quiz decks in the app. What you type - the deck's title and its questions - is saved to the same database as your lesson progress, under your anonymous identifier. It's handled the same way as the progress data described above.
Exporting a deck saves a file straight to your device through your browser's own download function. That step doesn't involve us at all. Importing a deck uploads the file's contents to our server so it can be saved to your session, the same as if you'd typed it into the form yourself.
Deleting a deck removes it, and any progress recorded against it, from our database.
Where data is stored
The app itself is hosted by Render (render.com). Lesson progress and any decks you create are stored in a database hosted by Neon (neon.tech). Both process this data on our behalf, purely to run the service - it is never sold or shared with any other third party.
Data retention
Progress data, and any decks you've created, are retained in our database, tied to your anonymous session identifier, for as long as you keep using the app. Clearing your browser's cookies - or, for the installed Android app, clearing the app's storage - removes your local session identifier immediately. That's the most direct way to stop the app recognizing you as the same visitor, but it also means losing access to any decks made under that identifier, since there's no account to sign back into. Exporting a deck to a file first is the way to keep a copy outside the app. If you still have questions about your data, you're welcome to reach out using the details below.
Children's privacy
This app is not directed at children and does not knowingly collect data from children.
Changes to this policy
If this policy changes, the "Last updated" date above will change to reflect it.
Contact
Questions about this policy: contact.grindster@gmail.com