Last updated: 14 August 2026
Gradeon is an app for managing trading card collections. It is a tracking tool: you keep an inventory of your cards in it, much as you would keep a spreadsheet.
That applies to trades too. Gradeon lets you compare your collection with another user's and update your inventory after a trade the two of you made yourselves. The app does not put users in contact, does not organise any trade and does not enable one to happen: it records the outcome, like a line you correct in a spreadsheet.
Here is what matters most, before the detail:
Gradeon is published by L. Cerny, an independent developer.
For any question about your data, or to exercise your rights: contact@gradeonapp.com
If you sign in with Google or Apple, we receive your email address and an account identifier. We receive neither your password nor your contacts. If you use "Sign in with Apple" and choose to hide your address, we only ever see a relay address provided by Apple.
Your reference country and currency, interface language, and — for each card game you follow — the language, condition and finish applied by default to the cards you add. These settings only serve to display the app the way you expect. You can change any of them at any time from your Profile.
The cards you record as owned, their condition, their language, any duplicate copies, your wish lists, and the estimated value of your collection over time.
When you propose or accept a trade, your username, the cards involved and the history of that trade are visible to the other user. Confirming a trade updates your two inventories inside the app — cards leave one collection and enter the other. It is an irreversible entry within the app, with no effect whatsoever in the real world: it triggers no shipment, does not prove a trade took place and guarantees nothing about it. Whether the trade actually happens never depends on Gradeon. The history of that entry is retained for both people.
Gradeon does not put users in contact, and no contact details are ever passed on. The app has no messaging and discloses your email address, phone number and postal address to nobody. Only your username is visible. Gradeon is limited to comparing collections and indicating which trades would be possible; making contact, negotiating and the trade itself all take place entirely outside the app, by whatever means you choose, and are unknown to us.
Collection sharing is on by default, for every game you follow. In practice, other users can see which cards you own, so as to spot possible trades with you. This sharing covers only the contents of your collection and your username — never your identity, and never any contact detail.
You can turn it off at any time, in a single tap, from Profile › Trading › Allow trading. As soon as it is off, other users can no longer see the contents of your collection, and you can change this setting as often as you like. There is a single switch: it applies to all of your card games.
This is the most important section of this policy, and it deserves to be precise.
Normal operation. When you scan a card, the photo is analysed on your phone: text recognition is performed by the component built into the operating system (Apple Vision on iOS). Only the text that was read — card name, number, set code — is then sent to card catalogues in order to identify the card. The photo does not leave your device. No external artificial-intelligence service receives it.
If you contribute to improving recognition. A setting in your Profile, called "Contribute to improving recognition", is on by default. While it is on:
These images are used exclusively to measure and correct recognition and centering errors. They may be reviewed by the app's administrator for that sole purpose. They are never published, never passed to a third party, and never used to profile you.
You can turn this contribution off at any time from your Profile, or by unchecking the box shown below the centering screen. As soon as it is off, no image and no scan data is uploaded at all. Images already uploaded are deleted along with your account, and you may request their deletion at any time by writing to us.
Finally, the app only requests access to your photo library if you choose to import an existing image instead of taking a photo. It does not access it at any other time and does not browse its contents.
When the app crashes or hits an error, a technical report is sent to Sentry so the defect can be fixed. Without these reports, a crash affecting a share of users stays invisible until someone takes the trouble to report it.
What the report contains: where in the code the error occurred (the “stack trace”), the device model, the iOS or Android version, and the Gradeon version.
What it does not contain: not your email address, not your username, not your account identifier, not your collection contents, not your photos, not your IP address. This is not an empty promise: the app strips these before sending, and that stripping is verified automatically on every change to the code.
No screenshot is ever attached to a report.
What it does contain nonetheless, and what we cannot remove. Two items are added by Sentry on its own servers, after the stripping performed by the app, and therefore escape it:
Reports are tied to no account: we can see that a defect exists, in which country and on which kind of device, but not who ran into it.
Your recent scan history, your interface language and your scan preferences are stored locally on your phone and are not transmitted. They disappear if you uninstall the app.
Gradeon relies on the following services. Each receives only what is stated.
A note about card images. The card artwork shown in the app is loaded from the servers of the catalogues above. As with any web page, those servers therefore see the IP address of your connection. This is a technical consequence of displaying remote images, not a collection choice on our part.
Your data is hosted with Supabase, in the European Union — the Frankfurt region, in Germany. Your account, your collection, your trades and your contribution images are not transferred outside the European Union.
Crash reports are likewise processed within the European Union: the Sentry project is hosted in the Frankfurt region.
The card catalogues and authentication services named above are operated from various countries, including the United States. What is exchanged with them concerns card identifiers rather than your identity — with the exception of Google or Apple authentication, if you use it, which concerns your email address.
When you delete your account, all of this data is erased — see below.
Under the General Data Protection Regulation, you have rights of access, rectification, erasure, restriction, objection and portability regarding your data. You can exercise them by writing to contact@gradeonapp.com.
Deleting your account, immediately and without contacting us. Go to Profile › Delete my account. Deletion is permanent and irreversible. It erases your authentication account, your profile, your collection, your wish lists, your trades and the contribution images you had uploaded.
Two honest clarifications about what follows a deletion:
You can also correct your username from Profile › Edit profile and change your password from Profile › Security.
If you believe your rights are not being respected, you may lodge a complaint with your national data protection authority. In France this is the CNIL, www.cnil.fr.
Access to your data is controlled row by row in the database: an account can only read and modify its own records, apart from what you explicitly choose to share. Email addresses are not accessible to any client account. Exchanges with our servers are encrypted in transit.
No system is infallible. Should an incident affect your data, we would inform you as promptly as possible and carry out the notifications required by regulation.
Gradeon is not intended for children under 13, and the app does not knowingly collect their data. If you are a minor, ask your parents for permission before creating an account, and in particular before making your collection visible to other users. Bear in mind that the trade itself takes place outside Gradeon: the app arranges no meeting and passes on no contact details.
This policy may change as the app evolves. The date of the last update appears at the top of this document. Any significant change in the data collected or in its recipients will be flagged in the app.
L. Cerny — contact@gradeonapp.com