For the Cairn appEffective: 25 August 2026Last updated: 25 August 2026
Before you start, please note
Reminders are not a guarantee. Notifications are scheduled by your device and its operating system, and may be delayed or never arrive — because of permissions, system limits, Low Power Mode, a device being switched off, and more. Do not rely on this app alone for dates that matter (section 5).
Backups are your responsibility. We run no servers and hold no copy of your data; if a device is lost or erased, we cannot recover anything (section 4).
Exported backups are not encrypted — anyone who gets the file can read it, so store it sensibly (section 4).
The app is currently free, with no subscriptions or in-app purchases (section 3).
1. Acceptance
These Terms of Service ("Terms") form an agreement between you and gwongsam, an independent developer ("we"), regarding the Cairn app ("the app"). By downloading, installing, or using the app, you confirm that you have read, understood, and agree to be bound by these Terms and the Privacy Policy. If you do not agree, please do not use the app.
If you are below the age of full legal capacity where you live, please use the app with the consent and guidance of a parent or guardian.
2. Licence grant and scope
Subject to your compliance with these Terms, we grant you a non-exclusive, non-transferable, non-sublicensable, revocable licence to install and use the app on Apple devices that you own or control, as permitted by Apple's Usage Rules, for your personal, non-commercial purposes.
You may not: (i) reverse engineer, decompile, or disassemble the app, or attempt to derive its source code, except where the law expressly permits it; (ii) rent, lend, sell, sublicense, distribute, or otherwise make the app available to others; (iii) remove or alter any proprietary notices; (iv) circumvent technical restrictions in the app or the platform.
3. Provided free of charge
The app is currently free: no subscriptions, no in-app purchases, no advertising, no cap on how many events you can create, and no features behind a paywall.
We reserve the right to introduce paid features in future versions. If we do, data you created beforehand will not be locked away, and we will update this page and make it clear in the app first. Any paid transactions would be handled by the App Store; refunds are governed by Apple's policies and can be requested at reportaproblem.apple.com.
4. Your data and your backups
Everything you create in the app belongs to you. We claim no rights over it and never access, use, or analyse it — because we run no servers and it never reaches us (see the Privacy Policy).
The unavoidable consequences, which you should be aware of:
If your device is lost, damaged, erased, or the app is deleted by accident, we cannot restore anything — we hold no copy to restore from.
iCloud sync depends on your own Apple Account and Apple's services, whose availability is outside our control.
Exporting a backup regularly, via Settings › Data › Export Backup, is your responsibility.
Exported backups are plain, unencrypted JSON. Once a file leaves the app — saved to a cloud service, sent through a messaging app — its security is between you and the service you chose.
Importing a backup appends rather than replaces and does not de-duplicate; importing onto a device that already holds the same events produces duplicates, which is expected behaviour.
5. Important: reminders are not guaranteed
The reminders in this app are a convenience, not a guarantee of any kind.
The app uses the operating system's local notification mechanism. Whether and when a notification arrives is up to your device and its OS, and it may be delayed or never delivered because of: notification permission not granted or later revoked, the device being off or out of battery, Focus modes and Do Not Disturb, Low Power Mode, the system limit on pending notifications (64 on iOS), system or app updates, changes to the time zone or system clock, storage or iCloud problems, and other factors outside our control.
For any date with meaningful consequences — including but not limited to medical appointments, medication, legal or administrative deadlines, limitation periods, contract expiry, payments and repayments, visa or document validity, and exam or application deadlines — do not use this app as your only reminder. Use a calendar, an alarm, or another independent method alongside it. We accept no liability for consequences arising from a notification that is not delivered, is delayed, or is incorrect.
6. Important: no professional advice
The app is a date-counting and reminder tool. It calculates and displays intervals between dates and does not constitute, and must not be treated as, medical, legal, financial, tax, or other professional advice.
Its date calculations involve time zones, daylight saving, repeat rules, and lunar conversions. We make every effort to get them right, but do not warrant that every result matches the reckoning of your jurisdiction or local custom in all cases. Where a deadline carries legal or financial consequences, rely on official sources or a qualified professional.
7. Acceptable use
You agree not to use the app for any unlawful or improper purpose, including:
Breaching the laws or regulations that apply where you live or use the app;
Infringing anyone's privacy, reputation, intellectual property, or other rights — including recording or storing another person's private dates without their consent;
Interfering with or disrupting the app or the system services it depends on;
Operating the app at scale by automated means, or attempting to bypass the system's permission mechanisms.
You are responsible for the lawfulness of whatever you enter or import into the app.
8. Intellectual property
The app and all of its components — including its code, interface design, icons, illustrations, the names "Cairn" and "司候", and the contents of this site — are our intellectual property and protected by copyright and related laws. These Terms grant a licence to use the app; they transfer no intellectual property.
System symbols, typefaces, and frameworks used in the app remain the property of their respective owners.
9. Changes and discontinuation
We may update, modify, add, or remove features at any time, and may end support for particular OS versions or devices. We try to avoid causing data loss, but please export a backup before any feature removal or format change.
We are under no obligation to maintain or update the app indefinitely. If we decide to discontinue it, we will make reasonable efforts to give advance notice and to ensure you can export your data first.
10. Disclaimer of warranties
To the fullest extent permitted by law, the app is provided "as is" and "as available", without warranties of any kind, express or implied, including merchantability, fitness for a particular purpose, non-infringement, accuracy, reliability, or uninterrupted operation.
We do not warrant that the app will be error-free or uninterrupted, or that every defect will be corrected.
Some jurisdictions do not allow the exclusion of implied warranties, so the above may not apply to you; in that case such warranties are limited to the shortest period the applicable law permits. Your statutory rights as a consumer are unaffected by these Terms.
11. Limitation of liability
To the fullest extent permitted by law, we are not liable for:
Any indirect, incidental, special, punitive, or consequential loss;
Loss, corruption, or unrecoverability of data;
Any date, deadline, or occasion missed because a notification was not delivered, was delayed, or was incorrect;
Any loss arising from your reliance on the app's calculations;
Any loss arising from the unavailability of iCloud, Apple Watch connectivity, or other third-party services.
In no event will our total liability relating to these Terms or the app exceed the amount you actually paid for the app in the twelve (12) months preceding the claim; as the app is currently free, that amount may be zero.
Nothing here excludes or limits liability that cannot be excluded or limited by law, including liability for wilful misconduct or gross negligence, or for death or personal injury.
12. Termination
You may end these Terms at any time by deleting the app. The licence terminates automatically if you materially breach these Terms. Sections 4, 8, 10, 11, and 13, along with any provision that by its nature should survive, remain in effect after termination.
13. Governing law and disputes
These Terms — their formation, validity, interpretation, performance, and any dispute arising from them — are governed by the laws of the mainland of the People's Republic of China (for the purposes of this clause, excluding its conflict-of-laws rules and the laws of the Hong Kong SAR, the Macao SAR, and Taiwan).
Any dispute arising out of or relating to these Terms shall first be addressed through good-faith negotiation; failing that, either party may bring proceedings before the competent People's Court at the developer's domicile.
If mandatory law where you live gives you the right to bring proceedings in your local courts or to have local law apply, this clause does not affect that right.
14. Apple-specific terms
The following are included to meet Apple's minimum terms for a developer's end-user licence agreement. You and we acknowledge:
Parties: These Terms are between you and us only, and not with Apple. We, not Apple, are solely responsible for the app and its content.
Scope of licence: The licence is as set out in section 2 and is subject to the Usage Rules in Apple's Media Services Terms and Conditions.
Maintenance and support: We are solely responsible for maintenance and support. Apple has no obligation to furnish any maintenance and support services.
Warranty: We are solely responsible for any warranties, express or implied. If the app fails to conform to any applicable warranty, you may notify Apple, and Apple will refund the purchase price (if any) for the app; to the maximum extent permitted by law, Apple has no other warranty obligation whatsoever with respect to the app, and any other claims, losses, liabilities, damages, costs, or expenses attributable to a failure to conform to a warranty are our sole responsibility.
Product claims: We, not Apple, are responsible for addressing any claims by you or a third party relating to the app, including product liability claims, claims that the app fails to conform to a legal or regulatory requirement, and claims arising under consumer protection, privacy, or similar legislation.
Intellectual property claims: If a third party claims that the app or your possession and use of it infringes their intellectual property rights, we, not Apple, are solely responsible for the investigation, defence, settlement, and discharge of that claim.
Legal compliance: You represent and warrant that (i) you are not located in a country subject to a US Government embargo or designated by the US Government as a "terrorist supporting" country, and (ii) you are not listed on any US Government list of prohibited or restricted parties.
Contact: Questions, complaints, or claims about these Terms may be addressed to gwongsam, gwongsam@gmail.com.
Third-party terms: You must comply with applicable third-party terms when using the app (for example Apple's Media Services Terms and the iCloud terms).
Third-party beneficiary: You and we acknowledge and agree that Apple and its subsidiaries are third-party beneficiaries of these Terms, and that upon your acceptance Apple has the right (and is deemed to have accepted the right) to enforce these Terms against you as a third-party beneficiary.
15. Miscellaneous
Entire agreement: These Terms and the Privacy Policy are the entire agreement between you and us regarding the app, superseding any prior oral or written communication.
Severability: If any provision is held invalid or unenforceable, the remainder stays in effect, and that provision shall be construed so as to come as close as lawfully possible to its original intent.
Waiver: Our failure or delay in exercising a right is not a waiver of it.
Assignment: You may not assign your rights or obligations without our written consent. We may assign these Terms in connection with a transfer, merger, or reorganisation of the business, without reducing the level of protection you enjoy.
Changes to these Terms: We may revise these Terms. Revisions will appear on this page with an updated date, and material changes will be made prominent in the app. Continuing to use the app after a revision takes effect means you accept it; if you do not, please stop using the app and delete it.
Cairn