Privacy Policy

Effective 5 August 2026. This Privacy Policy explains what Gemcheck (the "App") does — and does not — do with your information. Gemcheck is published by Lilin Systems ("we", "us"). It is built to measure cards on your phone: there is no account, no server of ours that your card images touch, and no analytics.

1. The short version. Every measurement Gemcheck makes happens on your iPhone, and the results stay there. There is no sign-up, no login, and no profile. There is one exception to "nothing leaves your device", and we would rather lead with it than bury it: if you subscribe to Gemcheck Pro and use the market feature, a picture of the card is sent once so that the card can be identified. §3 explains exactly what that involves. If you do not subscribe, no photograph ever leaves your device.

2. Photographs and camera access. Gemcheck asks for camera access for one purpose: to photograph the card you are measuring. The measurement itself is done entirely on your device — the perspective correction, the border detection, the millimetre widths, the corner and surface analysis — using Apple's Vision and Core Image frameworks together with our own on-device code. No photograph is uploaded in order to measure a card, and none is ever backed up to us or stored on our servers. You can deny or revoke camera access at any time in iOS Settings → Privacy & Security → Camera; without it, the App cannot photograph a card.

3. Identifying a card, and only for Gemcheck Pro. Pro adds a market section that shows what your card is selling for on eBay. To search for the right card, the App has to know which card it is — and a collector number alone is not enough, because a card shares it with every reprint of itself. So the first time you open the market section for a saved card, the App sends one picture of that card — the cropped, perspective-corrected front, not the original photograph and nothing of the background — to our service at gemcheck-api.vercel.app, which passes it to Scrydex, a trading-card data provider, to be identified.

What happens to it: our service holds the image only for the moment it takes to forward it, and writes it nowhere. Scrydex receives it to run the identification and returns a card name. The App then stores that name on your device and never sends the picture again for that card — identification happens once per card, not once per viewing.

The eBay search that follows carries text only — the card's name and number — and never an image. Listings shown in the App are loaded directly from eBay's own image servers, which means your device requests them from eBay in the ordinary way a web page would.

If you are not a Pro subscriber, none of this happens: the market section is not fetched at all, and no picture is sent.

4. What is stored, and where. All of the following live only on your iPhone, in the App's own storage:

• The photographs you take inside the App, and the perspective-corrected versions of them.
• Your measurements — border widths in millimetres, centering ratios, and the per-house results computed from them.
• Any edge positions you adjusted by hand, and the record that you adjusted them.
• Your saved binder of scanned cards.
• A local count of how many scans you have used this calendar month, so the free allowance can be enforced without an account.

Deleting the App permanently erases all of it. We hold no copy and cannot recover it.

5. What we do not collect. Gemcheck contains no analytics, no attribution, no crash-reporting and no advertising SDKs of any kind. It does not use the advertising identifier, does not ask for App Tracking Transparency permission, and does not track you across other apps or websites. It does not request your location, contacts, calendar, health data, microphone or photo library. We do not know your name or email address unless you choose to write to us. There is nothing to sell, and we do not sell or share personal data.

6. Subscriptions (Apple, and RevenueCat as our subscription processor). Gemcheck offers an optional subscription, Gemcheck Pro. Subscriptions are sold and billed by Apple through the App Store. Apple processes the payment; we never see or receive your card details, billing address or Apple Account credentials. Apple's handling of that transaction is governed by Apple's own privacy policy.

To know whether a subscription is active, we use RevenueCat, Inc. as our subscription-management processor. When subscription features are in use, RevenueCat receives an anonymous app-user identifier generated on your device — not your name, email or Apple Account — together with purchase and transaction data from Apple, such as which product was bought, when it renews, and whether it is active or has lapsed. That is the entire purpose: to answer "is this device entitled to Pro?". RevenueCat acts as a processor on our behalf and is bound by its own privacy commitments; see RevenueCat's privacy policy. RevenueCat receives no photographs, no measurements and no card data of any kind — the subscription layer and the measurement layer share nothing.

For completeness, and because we would rather be precise than reassuring: at the time of this policy's effective date, billing is not yet enabled in the App. No RevenueCat key is configured in the shipping build, so nothing is sent to RevenueCat at all. This section is written to describe the arrangement accurately once purchases go live, so that it does not need to change under you.

7. Third parties, in full.

• Apple — App Store distribution and, once enabled, payment.
• RevenueCat — subscription status only, as described in §6.
• Scrydex — receives one picture of a card, for Pro subscribers only, to identify it (§3).
• eBay — receives the card's name and number as a search, never an image; your device loads listing pictures from eBay's servers when the market section is on screen (§3).

That is the complete list. There is no advertising network, no data broker, and no analytics provider. If that list ever grows, this page changes first.

8. Your rights and the legal basis. Because Gemcheck collects no personal data on our side, there is in practice nothing of yours for us to access, export, correct or erase — and deleting the App erases everything on the device. Where data protection law such as the UK GDPR or EU GDPR applies, our legal bases are: performance of a contract for the minimum purchase and entitlement data needed to give you a subscription you paid for (§5), and legitimate interests in operating and supporting the App. You retain your statutory rights of access, rectification, erasure, restriction, objection and portability, and the right to complain to your local supervisory authority. Email us and we will answer honestly, including where the honest answer is "we hold nothing about you".

8. Children. Gemcheck is rated 4+ and contains no user-generated content, no messaging and no advertising. It does not knowingly collect personal information from anyone, of any age, including children under 13 (or under 16 where local law sets that threshold) — because it does not collect personal information at all.

9. Security. Your photographs, measurements and binder are protected by iOS's own protections: app sandboxing and, when you set a device passcode, file-system encryption. We hold no server-side copy of any of it to secure — or to lose.

10. Changes. If we update this policy we will change the effective date above, and for material changes — in particular any change to what leaves your device — we will say so plainly on this page.

11. Contact. Questions about privacy, or want to check a claim on this page? Email gemcheck@lilinsystems.xyz.