Privacy Policy.
Effective date · June 8, 2026
Hydration Hostage (“the app”) is a macOS hydration reminder developed by Rexinno (“we”, “us”). We built it to be private by design. This policy explains what the app does — and does not — do with your information.
Camera
When you start a hydration check, the app uses your Mac’s camera to confirm you bring a cup or bottle to your mouth. This happens entirely on your device, in real time, using Apple’s on-device Vision and Core ML frameworks. Camera frames are analyzed momentarily and then discarded. No images or video are ever recorded, saved, or sent anywhere — not to us, and not to any third party.
Face Data
To verify that you bring a cup or bottle to your mouth during a hydration check, the app uses Apple’s on-device Vision framework to detect facial landmarks — specifically, the approximate position of your mouth in the current camera frame.
What is collected: Temporary, in-memory facial-landmark positions (such as the location of your mouth) computed from the live camera frame during an active hydration check. The app does not perform facial recognition or identification, and does not create a faceprint or any biometric template that could identify you.
How it is used: Solely to determine, on your device, whether a drink container is near your mouth so the app can confirm a sip. It is used for no other purpose.
Sharing / third parties: Face data is never shared with us or any third party. All processing happens locally on your Mac using Apple’s Vision and Core ML frameworks. The app contains no analytics, advertising, or third-party SDKs, and uses no server.
Storage & retention: Face data is processed momentarily in memory and discarded as soon as each camera frame is analyzed. It is never recorded, written to disk, saved, or transmitted, and is not retained.
Information stored on your device
Your settings and usage stats (such as reminder interval, mode, streak, and sip count) are saved locally on your Mac using the system’s standard preferences storage. This information stays on your device, is not transmitted to us, and is removed if you delete the app.
No accounts, no tracking
The app has no sign-up or login. We do not use analytics, advertising, tracking technologies, or third-party SDKs, and we do not build a profile of you.
Purchases
The app offers a one-time in-app purchase to unlock unlimited checks. Purchases are processed entirely by Apple through the App Store. We never see or receive your payment details. Apple’s handling of that transaction is governed by Apple’s Privacy Policy.
Data sharing
We do not sell, rent, or share your data, because we don’t collect any.
Children
The app is not directed at children and does not knowingly collect any information from anyone.
Changes to this policy
If we update this policy, we’ll revise the “Effective date” above and post the new version on this page.
Contact
Questions? Email us at huy@rexinno.com.