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Tidal Contrast

Privacy Policy

Your Body Data Stays Yours

Tidal Contrast has no account, no ads and no analytics that include health data. Your sauna and cold sessions stay on your Apple Watch, your iPhone and in Apple Health.

This policy describes the first version of the app, which is in development. We will check it against the finished app before launch. Last updated 27 October 2026.

  • No AccountNo Sign-Up Needed
  • On DeviceSessions Stay on Your Watch and iPhone
  • Apple HealthWith Your Permission Only
  • Status OnlySpotter Messages Never Include Health Data

Who We Are

Tidal Contrast is made by Mason Technologies Limited, a company registered in England and Wales, which is the data controller for this website. You can reach us at support@tidalcontrast.app.

What the App Reads

With your permission, the app reads heart rate, heart rate variability, resting heart rate and sleep from Apple Health, so it can show your sessions in context. On Apple Watch models with a water temperature sensor, it reads water temperature and depth to notice when you go in and come out of the water. None of this is copied to a server.

What the App Stores

  • Each session is kept on your iPhone and Apple Watch, and written to Apple Health if you allow it: for sauna and steam, the start time, rounds, time in the heat and heart rate; for cold water, the start time, time in the water, water temperature and heart rate.
  • Your first-launch screening answers and your settings are kept on your iPhone, with a copy on your Watch so it can set your time limit.
  • Nothing is stored by us. We have no account system and no copy of your data.

The Spotter

If you choose a spotter, the app sends that person a short status message: that you have started, that you are out, or that you are overdue. It never includes your heart rate, water temperature, screening answers or location. We will describe exactly how the message is sent before launch.

Analytics and Advertising

The app has no advertising and does not sell or share your data. It contains no analytics that include health data, and no third-party tracking.

Export and Delete

You can export your sessions as a CSV file from the iPhone app. Deleting a session or all your data removes it from the app and from Apple Health, where the app wrote it. Deleting the app removes everything it stored on your devices.

This Website

  • This site loads its fonts, scripts and images from its own server and sets no advertising or tracking cookies.
  • Our web server keeps standard access logs (IP address, page and browser) for security, for a short period.
  • If we add analytics later, we will name the tool here and prefer a privacy-first one.

Your Rights

Under UK data protection law you can ask what we hold about you, and ask us to correct or delete it. Because the app keeps your data on your devices, we usually hold nothing about you. If you are unhappy with how we handle your data, you can complain to the Information Commissioner’s Office at ico.org.uk.

Changes

If this policy changes, we will update this page and the date at the top.