Privacy Policy
Last updated: 31 July 2026
The short version
DiskDyno does not collect anything about you. It has no account system, no analytics, no advertising, no tracking, and no code that sends data anywhere. Your benchmark results are a file on your device. We never receive them, because the app has no way to send them.
That is the whole policy. The rest of this document explains it precisely, and is honest about the one thing we do learn: what Apple tells us about our own app.
1. Who we are
DiskDyno is published by Johnston Software & Services, LLC, an Oregon limited liability company.
Notice address:
Johnston Software & Services, LLC
PO Box 230614
Tigard, OR 97281
United States
Contact: support@diskdyno.com
2. What DiskDyno collects
Nothing.
DiskDyno contains no networking code of its own. We operate no server, and there is no code in this app that sends your results, your settings, or anything else about you anywhere. This is not a promise about our intentions, it is a property of the binary: if the app could transmit your data, it would need code to do it, and there is none.
The one exception is the purchase itself. When you buy DiskDyno Pro, Apple's own software inside the app talks to Apple to confirm the purchase. That connection is between you and Apple, it carries no benchmark data, and we do not see it. See §5.
Specifically, DiskDyno has:
| User accounts or sign-in | None |
| Analytics or telemetry SDK | None |
| Crash reporting SDK | None |
| Advertising or ad identifiers | None |
| Cloud sync or backup service | None |
| Backend service we operate | None |
3. What stays on your device
DiskDyno stores four kinds of information locally, and only locally:
Your saved results. Every benchmark you choose to save is written to a file inside the app's own storage. So that a saved result is still meaningful months later, that file records more than the headline speed. It holds:
- the measured read and write speeds, the sustained figures, and the speed of each
individual segment of the run
- the confidence verdict and the specific findings behind it
- the label you typed, and the date and time
- information about the drive you tested: its name as the drive reports it, its format,
its total and free capacity, and whether it is internal or removable
- information about your device: the hardware class we use to work out the port's
physical speed limit, and the battery percentage and charging state at the start and end of the run, because running on battery can slow a device down and is one of the things that lowers a confidence verdict
A drive's own name is whatever you or your camera called it, so it may contain anything you chose to put in it. All of this stays on your device. None of it is transmitted, because there is nothing to transmit it with.
Your settings. Two preferences, the test size and the iteration count, are stored in the app's own preferences area.
Whether you have unlocked Pro. If you buy DiskDyno Pro, the app records that fact as a single yes-or-no value in the same preferences area, so that it does not have to ask Apple again every time you open it. It records only that the unlock happened. It stores no payment details, no order number, and nothing else about the transaction.
Reports you generate. When you export a result as a PDF, that file is written to the app's own temporary storage before you share or save it. It contains the same information as the saved result it came from.
All four are removed when you delete the app. If your device is included in an iCloud or computer backup, your saved results are included in that backup, because they are ordinary app files. That backup is between you and Apple. We are not part of it and cannot read it.
4. The drives you test
DiskDyno never scans or enumerates the volumes attached to your device. It has no list of your drives and no way to build one. It sees only what you hand it.
To test your device's own internal storage, DiskDyno uses its own private storage area and needs nothing from you. To test any other drive, you select a folder on it through the standard iOS file picker, and DiskDyno gets access to that folder and nothing else. The drive-to-drive transfer test asks you to pick two folders, one on each drive, and gets access to those two and nothing else.
What DiskDyno writes to a drive you select. When you pick a folder, DiskDyno immediately writes a tiny hidden file named .diskdyno-write-probe into it and deletes it again. This is how it finds out whether the drive is writable before offering you a test that would fail. It happens once, when you pick the folder, whether or not you go on to run anything.
During a run, DiskDyno creates its own test file in that folder, plus a small second file used to check that the cache bypass is genuinely working. It deletes each one when it is finished with it, and it creates a fresh test file for each repeat of the test.
**DiskDyno does not read, catalogue, index, or transmit the contents of the drives you test.** It never opens a file it did not create. It measures how fast its own temporary file moves on and off the device, and it reads the drive's published details, its name, format and capacity, in order to label and interpret the result.
5. Purchases
DiskDyno is free to start. Some capabilities are part of a one-time purchase called DiskDyno Pro. There is no subscription.
Purchases are handled entirely by Apple through the App Store. We never see, receive, or store your payment card, your Apple Account credentials, or your billing address. What we receive from Apple is the fact that a purchase on our product succeeded, which is what unlocks the feature on your device.
Apple's handling of your purchase is governed by Apple's privacy policy, not this one.
6. What Apple tells us
This is the one place where we learn anything, and we would rather state it plainly than let the "we collect nothing" summary overstate our position.
If you have agreed to share analytics with developers in your device settings, Apple may show us aggregated, non-identifying reports about DiskDyno: how many people installed it, roughly which device models and OS versions are in use, and anonymised crash logs. If you leave a review on the App Store, we see the review, along with whatever display name you chose to publish it under. If you contact us for support, we see whatever you put in that message.
We do not receive your name, your email address, your device identifier, your location, or any of your benchmark results. Apple's reports are statistics about our app, not records about you, and we cannot use them to identify or contact any individual.
You can turn the analytics sharing off on your device under Settings, Privacy & Security, Analytics & Improvements.
7. Tracking
DiskDyno does not track you. We do not collect data that is linked to you, we do not share data with data brokers, and we do not use your activity in this app to target advertising anywhere.
Because DiskDyno does not track, it never presents the App Tracking Transparency prompt. Our privacy manifest declares NSPrivacyTracking as false and lists no tracking domains and no collected data types.
8. System APIs we use, and why
Apple requires apps to declare a reason for using certain system capabilities. These are the three DiskDyno declares:
| Capability | Why DiskDyno uses it |
|---|---|
| Elapsed-time measurement | To time how long a read or write pass takes, which is the entire measurement. It is used to compute a duration and never to derive a device fingerprint |
| Available disk space | To check that a drive has room before allocating a test file, so a run fails cleanly instead of filling your drive, and to show you the drive's capacity alongside its result |
| App preferences | To remember your two settings between launches, and whether you have unlocked Pro, in DiskDyno's own preferences only |
DiskDyno also reads two things that Apple does not require a declaration for, and we mention them because §3 records both of them in your saved results: your device's hardware class, which tells us the physical speed limit of its port, and the battery level and charging state, because a device on battery can run slower and that affects how much a result should be trusted.
None of these produces anything we receive. The app sends none of it anywhere, and the only network connection it makes at all is Apple's own, when you buy the Pro unlock, as described in §2 and §5.
9. Children
DiskDyno is a storage measurement tool for a general audience. It is not directed at children, and it collects no personal information from anyone of any age. Because we collect nothing, we hold no children's data.
10. Your rights
Privacy laws including the GDPR and the CCPA give you rights to access, correct, delete, and port the personal information a company holds about you, and to know whether it has been sold or shared.
We hold no personal information about you. There is nothing for us to produce, correct, delete, or port, and we have never sold or shared personal information, because we have never had any. Your saved results are already entirely in your possession: they are files on your device, you can export them yourself, and deleting the app deletes them.
If you believe we hold information about you and want to exercise a right over it, write to the address in §1 and we will respond.
11. Security
The security question for most apps is how they protect the data they transmit and store on a server. DiskDyno transmits nothing and we operate no server, so that entire category of risk does not apply here.
Your saved results sit inside DiskDyno's own storage on your device, protected by your device passcode and iOS file protection like any other app's data.
12. Changes to this policy
If we change what DiskDyno does, we will change this policy in the same release, not after it. The "last updated" date at the top will change with it.
We will not quietly add data collection to a later version. If a future version of DiskDyno ever collects anything, that will be stated here before that version ships.
13. Contact
Johnston Software & Services, LLC
PO Box 230614
Tigard, OR 97281
United States