Privacy Policy & Disclaimer

1Introduction

This is the Privacy Policy and Disclaimer for TechRef, an iOS app developed by Flying Dev Lab (空飛ぶ研究室).

TechRef is a unit conversion and engineering reference tool for technical professionals. It is built on a simple principle: your data belongs to you, and it stays on your device.

Please read this page before using the App. The Disclaimer section describes important limitations on how the App's output should be used.

2Data Stored on Your Device

TechRef stores the following on your device only:

• Conversion history (values, tolerances, units, labels, memos, timestamps)
• Sheets data (part names, measurement point names, dimensions, memos)
• App settings (decimal places, appearance, unit preferences)

History and Sheets are saved as files in the App's Application Support directory. Settings are saved in the standard iOS preferences store. Deleting the App removes all of this data from your device.

The Developer has no access to any of it.

3Network Activity

TechRef's core features — unit conversion, tolerance calculation, the reference tables, and saving your data — work entirely offline. No network connection is required to use them.

There are no analytics SDKs, no crash reporting services, no advertising SDKs, and no third-party libraries that transmit data.

The App itself connects to the network in only two cases, both initiated by you:

• Purchasing or restoring the in-app purchase — handled by Apple through the App Store (see In-App Purchases)
• Tapping the Support link in Settings — this website opens in your browser

In neither case is any dimensional data you entered transmitted. Purchase traffic goes to Apple and to no one else, and it contains none of the values you entered in the App.

Usage statistics collected by Apple. Because the App is distributed through the App Store, Apple — as the platform operator — aggregates statistics such as installs, launches, session length, and purchases, and provides them to the Developer in anonymized, aggregated form. If you have enabled diagnostic data sharing in your iOS settings, crash reports are provided in the same way. All of this is managed by Apple, and the Developer can neither enable nor disable it.

What these statistics never include: the dimensions, tolerances, part names, measurement point names, labels, memos, conversion history, or Sheets content you enter. The App never transmits any of it, so neither Apple nor the Developer can obtain it. Apple knows that the App was used — not what you calculated.

The only way your data leaves the device is the clipboard copy and CSV export described in Exporting Your Data, and both happen only when you choose to do it.

4iCloud Backup

TechRef does not use CloudKit and does not synchronize your data with any cloud service.

However, if you have enabled iCloud Backup in your device settings, iOS may include TechRef's data files in your device backup, along with data from your other apps. This is a standard operating system feature managed entirely by Apple. The Developer neither initiates nor has access to these backups.

This is what allows your history and Sheets to be restored automatically when you set up a new device. If you prefer not to have this data backed up, you can disable iCloud Backup for TechRef in the iOS Settings app.

Backup handling is governed by Apple's Privacy Policy.

5Exporting Your Data

TechRef lets you take your data out of the App in two ways:

• Copy — conversion results or sheet data are placed on the system clipboard
• Save to Files — a CSV file is written to a location you choose in the Files app

Both actions are initiated by you, and the App does not send data anywhere on its own. Once data leaves the App, its handling — including where you paste it, who you send it to, and any cloud storage location you select in the Files app — is outside the App's control and is your responsibility.

If you work with dimensional data that your organization treats as confidential, please follow your own internal policies when exporting.

6Advertising and Tracking

TechRef contains no advertisements.

The App does not use the advertising identifier (IDFA), does not request App Tracking Transparency permission, and does not track you across apps or websites. There is no profiling, no behavioral analysis, and no data broker relationship of any kind.

This is a design decision, not a temporary state. TechRef is a professional tool, and it will not carry advertising.

7In-App Purchases

TechRef is free to download. Unit conversion, tolerance calculation, and the reference tables can be used without any usage limit, whether or not you purchase.

Saving to History and Sheets is free up to a certain number of saves. Beyond that, the frequency of saving is limited. A one-time (non-consumable) in-app purchase removes that limit permanently. The specific number, the nature of the limit, and the price are shown on the App Store product page and on the purchase screen inside the App.

All payment processing is handled by Apple through the App Store. The Developer will not receive your payment details, card information, or any personal information associated with the transaction. See Apple's Privacy Policy for how Apple handles that data.

Restoring a purchase. A purchase is tied to your Apple Account, not to a particular device. "Restore Purchases" in Settings asks Apple whether that account holds the purchase. The query is completed between your device and Apple; the Developer neither stores nor receives your Apple Account. Use it to restore your purchase after changing devices or reinstalling the App.

Any change of this kind will be reflected on this page before it takes effect.

8Sharing of Information

The Developer does not sell, share, or transfer user information to third parties, for the simple reason that no user information is collected in the first place.

There is no data to disclose to advertisers, analytics providers, or data brokers. In the event of a legally binding request from a competent authority, the Developer has no user data that could be produced.

9Children's Privacy

TechRef is a professional engineering tool and is not directed at children.

Nevertheless, because the App collects no personal information from anyone of any age, it presents no children's privacy concerns. There is no data to protect, share, or delete — for any user.

10Disclaimer

Reference information only. Conversion factors, reference tables, and calculated results provided by the App are reference information based on publicly available standards and definitions. They are not certified data and carry no warranty of accuracy, completeness, or fitness for any particular purpose.

Verification is your responsibility. Before applying any value from the App to design, machining, inspection, or procurement, you must verify it against the applicable official standard, the controlling drawing, and your organization's internal procedures. The App is intended to assist that process, not to replace it.

Limits of the tolerance calculation. The center value and range shown by the App are the result of arithmetic on the values you enter. The calculation does not account for machining method, tooling condition, measurement uncertainty, material properties, thermal expansion, fit class, or any other physical or process factor. A mathematically valid center value is not necessarily an appropriate machine setting.

Rounding and display precision. Results are rounded to the number of decimal places selected in Settings. Rounding may introduce error, and displayed values may differ from the full-precision internal result. Choose a precision appropriate to your tolerance band.

Unit selection. You are responsible for selecting the correct unit and category for your input. The App cannot detect an incorrect unit assignment.

Limitation of liability. To the maximum extent permitted by applicable law, the Developer shall not be liable for any direct, indirect, incidental, or consequential damages arising from use of, or inability to use, the App — including but not limited to defective parts, rework, production delay, equipment damage, personal injury, or economic loss.

Availability. iOS updates or changes in the device environment may affect the App's behavior without prior notice. The Developer may modify or discontinue the App without prior notice, and is not liable for data loss resulting from such changes.

11Governing Law

This policy is governed by the laws of Japan. Any dispute arising in connection with this policy shall be subject to the exclusive jurisdiction of the court having jurisdiction over the Developer's location as the court of first instance.

12Changes to This Policy

This policy may be updated as the App evolves. The revised version takes effect when it is posted on this page, and the effective date at the top of the page will be updated accordingly.

Because no data is collected, changes to this policy cannot affect data already held about you. If a change materially affects how the App behaves — for example, the introduction of in-app purchases — it will be published here before that change reaches users.

13Contact

Questions, corrections, and feature requests are welcome. If you find an error in a conversion factor or a reference table, please report it — accuracy reports are given priority.