Privacy policy

Last updated: 3 November 2026

This policy explains what happens to your information when you use DermStudy (the app) and this website. DermStudy is provided by Duzzlr Pte. Ltd. ("we"). Contact: [email protected].

The short version

• No accounts. You don't sign up inside the app.
• Your study progress is stored only on your device, in your browser's local storage. We can't see it.
• The app has no analytics, advertising or tracking code.
• When you unlock the app, your license key is sent to our license-check service, which passes it to Gumroad to confirm the purchase and records which (randomly identified) device is using it.

What the app stores on your device

Your answers, progress, settings, streak and the license confirmation are saved in your browser's local storage, and app files and images are saved in the browser cache so it works offline. This stays on your device until you clear it, use "Erase all progress" in the app, or uninstall it. If you export a progress file, you decide where it goes.

License check

To unlock the full app, your license key (and our product ID) is sent over HTTPS to a small server function hosted on Cloudflare, which forwards it to Gumroad's license API and returns whether the key is valid and not refunded or disputed. The app repeats this check quietly in the background at most about once a week when you're online; if the check can't connect, nothing changes and the app keeps working offline.

One device per license. To keep each license to one device at a time, the app creates a random device ID on your device (it contains nothing about you or your phone). Our server stores one small record per license on Cloudflare: a salted SHA-256 hash of your key (not the key itself), the random device ID currently using it, the date it was first activated and last checked, and the dates of any moves to another device in the last 30 days (to apply the limit of 3 moves). We don't store your name, email, IP address or the key in readable form, and we don't log keys. We use the record only to run the license and to help you if you contact support; you can ask us to delete it at [email protected] (the license will then be re-activated on the next device that checks in).

Inside the unlocked app, a partly hidden version of your key (for example the first 8 and last 4 characters) is shown faintly on screen so that a shared or leaked copy can be traced to its licence.

Purchases

Payments are handled by Gumroad. Gumroad processes your name, email and payment details under its own privacy policy (gumroad.com/privacy). We receive the sale details Gumroad provides to sellers, such as your email address, to deliver your purchase and support.

Hosting

The app and this website are hosted on Cloudflare Pages. Like any web host, Cloudflare processes technical data such as IP addresses to deliver pages and protect against abuse, under its own privacy policy (cloudflare.com/privacypolicy). We do not add analytics or tracking scripts to the app or this website.

External links

Some screens link to outside sites (for example, guideline bodies). Those sites have their own policies.

Children

DermStudy is meant for medical students and health professionals and is not aimed at children.

Your rights

Depending on where you live (for example under the Philippine Data Privacy Act or the GDPR), you can ask about, correct or delete personal data we hold. Email [email protected].

Changes

We'll update this page if anything changes and note the date above.