Tidemark Privacy Policy

Effective 14 October 2026

Tidemark is a calendar app. Your schedule says a lot about your life, so Tidemark is built so that we never receive it. The short version: Tidemark does not collect your data.

Information we collect

None. Tidemark has no accounts, no analytics, no advertising and no third-party tracking or SDKs. We do not receive, store, share or sell any information about you.

Calendars and reminders

With your permission, Tidemark reads and edits the events and reminders already on your device through Apple's Calendar and Reminders frameworks. That includes accounts you have added in your device settings, such as iCloud, Google, Outlook or Exchange. Changes are saved back to those accounts by your device. Tidemark itself never sends this information to us.

Location and travel time

If you allow location access, Tidemark uses your approximate location on your device to estimate travel time to upcoming events. Travel estimates and place lookups are provided by Apple Maps under Apple's privacy policy. Your location is not sent to us or stored by Tidemark.

Weather

If weather is turned on, your device asks Apple Weather for the forecast at your approximate location (or the home address you entered). These requests are handled by Apple under Apple's privacy policy; the forecast is kept on your devices and is never sent to us.

Booking links

When you share a booking link, the open times you chose (and the name, meeting title and optional email you entered) are encoded inside the link itself, after the “#”. Web browsers never send that part of a link to any server, including ours. Your calendar is never shared.

When a guest books, their request (the time, their name, and the email, place and note they choose to add) is encrypted in their browser with a key that only your devices hold, and passed to your devices through ntfy.sh, an open-source message relay, which keeps it for up to 12 hours. The relay, and we, can't read it. Tidemark on your devices decrypts it and asks you to accept or decline; nothing goes on your calendar until you accept. Your answer goes back to the guest the same way: encrypted on your device with a key only their browser holds, and passed through the relay to their booking page. A guest who later changes or cancels their booking sends the change the same way; their browser remembers the booking (and the key to read your answer) so they can find it again, and their private link carries it to their other devices. If the relay can't be reached, the guest can send you the request by email or message instead.

Sync between your devices

Tidemark's own settings, such as hidden calendars, feed links, templates and travel preferences, sync between your devices through your private iCloud account, which is controlled by you and Apple. The Apple Watch app communicates directly with your iPhone.

Calendar feeds

When you subscribe to a calendar feed (a webcal or .ics link), your device downloads it directly from the address you entered. That server may see your IP address, as with any web request.

Purchases

Tidemark Pro subscriptions and the lifetime purchase are processed entirely by Apple through the App Store. We never see your name, payment details or Apple Account.

Notifications

Time-to-leave alerts are scheduled locally on your device. Nothing is sent to a server, and you can turn them off in the app or in Settings.

Contacting support

If you email us, we receive your email address and whatever you choose to write. We use it only to reply and never add you to a mailing list.

Children

Tidemark does not knowingly collect information from anyone, including children.

Changes to this policy

If this policy changes, the updated version will be posted at this address with a new effective date.

Contact

Questions about privacy: raghav_c@kalbhor.com