How DustFox keeps your photos on your device
“On-device” is easy to write. Here is what it means in DustFox, piece by piece, so you can check it yourself.
Network use: Pro purchases and anonymous statistics
DustFox never sends photos or scan results anywhere. The internet is used for two things: buying, restoring and checking Pro through Apple's StoreKit and RevenueCat, and sending anonymous usage statistics (which screens and features are used, how much space was freed) to PostHog's servers in the EU. Scanning works with the network switched off, which is the simplest way to check. Settings › Anonymous statistics turns the statistics off.
There is no account
No sign-up, no email, no login. There is nothing to sign in to, and nothing DustFox records is tied to your name or your Apple Account.
One third-party library, for purchases only
Since 1.1.7, DustFox uses RevenueCat to verify App Store purchases and decide whether Pro is active. It is the only third-party code in the app: it receives purchase records under a random ID, never your name or payment details, and it does not read the advertising identifier. There are no analytics, crash-reporting, advertising or attribution libraries; the anonymous statistics are sent by a few lines of DustFox's own code. Version 1.1.2 briefly included Meta's SDK to count installs from our ads; it was removed completely in 1.1.3.
Analysis happens on the device
Fingerprinting, comparison, sharpness scores, compression and re-encoding all use Apple's frameworks on your iPhone or iPad. Your photos are read where they are and never copied elsewhere.
The widget shares through an App Group
The Home Screen widget reads the numbers from the last scan through an App Group, a folder on the device that only DustFox and its widget can open. The weekly digest is a local notification scheduled on the device.
Share cards carry only numbers
The Gallery Report Card and Group Bill are images drawn on the device from counts and sizes. No photo goes on them, and sharing goes through the standard iOS share sheet.
Permissions are minimal
DustFox asks for photo access and nothing else. Limited access (“Selected Photos”) is fully supported. Notification permission is requested only if you turn on the weekly digest.
And this website?
This site sets no cookies and loads no third-party scripts. Visits are counted with Cloudflare Web Analytics, which does not use cookies or fingerprinting.
