Privacy Policy

1. In Short

Derslio is a study tracking app. We process your data only to make the app work: syncing your plan across your devices, analysing your mock exams and producing your statistics.

We do not show ads, we do not collect advertising identifiers and we do not sell your data.

2. Services We Use

We use Google Firebase for authentication, database and file storage, and Google Cloud Run and Supabase on the server side. When you sign in with Google or Apple, authentication takes place at that provider; we only receive the account identifier and email address the provider passes to us.

In the Camps feature, the titles and durations of the YouTube playlist and videos you add are read from YouTube, and the videos are watched in YouTube's own player. This feature uses YouTube API Services; by using it you agree to the YouTube Terms of Service (youtube.com/t/terms). The Google Privacy Policy applies to information shared with YouTube while you watch (policies.google.com/privacy).

When an error occurs in the app, a technical record is sent to Firebase Crashlytics and to our own error logs so that we can find and fix the problem: the error details, the app and operating system version, the device model and, if you are signed in, your account identifier. These records are used only for debugging and are not processed for advertising or profiling.

On the derslio.app website, Google Analytics cookies are used only if you allow them in the bar at the bottom of the page: to measure which pages are visited, where the visit came from (e.g. a search engine) and the browser and device type. This information is used only to improve the site and is not processed for advertising or profiling. If you do not allow it, no cookie is written; only a cookieless, anonymous page view count is sent to Google. You can change your choice at any time with the "Cookie preferences" link in the site footer. The Derslio app itself contains no analytics or screen recording.

These services process your data on our behalf; we do not allow them to use it for their own purposes.

3. What Is Kept on Your Device

The app works on your device first: your tasks, sessions, mistake notebook, camps and preferences are stored in your device's local storage; if you are signed in, they are synced to the cloud in the background and also appear on your other devices. This lets you work offline too.

If you are signed in, the question photos you add to your mistake notebook are uploaded to a folder that belongs only to you in Firebase file storage. No one, including your friends, can see these photos; access is enforced by database and storage rules. When you delete an entry or a photo, the copy in the cloud is deleted too. When you sign out, the notebook and photos are removed from that device and remain in your account.

In the web version, the same information is kept in the browser's local storage. We do not use advertising or tracking cookies.

4. Free Version and Subscription

Derslio's free version has no time limit: we do not ask for payment details and nothing is ever charged automatically. In the free version, some features can be used a limited number of times (see the Terms of Use, "Free Version and Premium").

We do not collect any additional data to apply these limits. They are calculated from the number of records you already keep: tasks, camps, mistake notebook entries, mock exam results and countdowns. Only the number of PDF study plans you create is stored separately. If you are signed in, this number is saved to your account; if you use the app as a guest, it is saved only on your device.

Earlier versions of the app kept a random identifier specific to your device and a one-way digest of information describing the device, so that the seven-day trial could be used only once per device. The trial has been removed. These records are no longer created or used, and existing records are deleted.

If you subscribe, your subscription runs through the App Store or Google Play; we do not see or store your payment details. We keep only whether a subscription exists and which plan it is.

5. Security

Data is encrypted in transit. Only the account owner can access the records on the server; this is enforced by database rules and is not left to the app's good intentions.

We never see your password; authentication is performed by the provider.

6. Retention and Deletion

Data associated with your account is kept for as long as your account remains open.

You can export all your data from the page that opens when you tap your name on the Profile page. If you want to close your account completely, you can use the "Delete Account" step on the same page; this cannot be undone.

To clear only your content without closing your account, the "Delete all data" step on the same page deletes your tasks, sessions, mock exams, mistake notebook (including question photos) and camps from both your device and the server.

When you delete your account, your sign-in and your data are permanently deleted: your tasks, study sessions, notes, mock exam results, mistake notebook and question photos, camps, friendships and the files you uploaded. All that remains is an empty record showing that the account was closed; it contains no name, email or photo. This record exists so that users who were your friends see "deleted user" instead of a broken card.

If you have a subscription, deleting your account does not cancel it automatically — subscriptions are managed by the App Store or Google Play and must be cancelled there.

The exam report file you upload is deleted from the server once analysis is complete; only the numbers remain.

7. Children

Derslio is not designed for children under 13 and must not be used by anyone under the age of 13.

Derslio is intended for students preparing for exams and may have users who are minors. If you are under eighteen, you should use the app with the knowledge and consent of a parent or guardian.

We do not knowingly collect data for advertising or profiling purposes.

8. Changes

This policy is updated as the app changes. You will be informed within the app when there is a significant change. The date at the top of the text shows the last update.

You can write to us with any questions about this text.