Altimeter privacy policy

Effective November 12, 2026

Altimeter is a free elevation app for iPhone and Android and a web app at altitude.hertzmc.com, made by Jayden Hertz. This page explains what it does with your information.

Your location

• Altimeter uses your phone's location (GPS) only to work out your elevation.
• Your GPS position is processed on your phone. Altimeter never sends it to us or anyone else, never stores it on a server and doesn't save your position on the phone either. (The ad in the apps gets your IP address, which shows roughly your city; see Ads below. We don't pass your GPS location to the ad.)
• It uses your location only while the app is open on your screen. It does not track you in the background.

The air pressure sensor

Most phones have an air pressure sensor (barometer). The apps read it to measure changes in elevation more smoothly. On iPhone this sensor is part of "Motion & Fitness", so iPhone asks you about that once; Altimeter reads only air pressure from it, nothing about your activity. The readings stay on your phone.

What's saved on your phone

Your choice of feet or meters and your current trip (climb, descent, lowest and highest point, and the elevation profile, which holds heights but no positions) are saved on your phone so they're still there next time. If you set your elevation by hand, that setting is kept for a few hours. "Reset trip" clears the trip, and uninstalling the app deletes everything. The Android app doesn't copy anything to a Google backup. The web app keeps the same things in your browser's storage on that device.

App updates

When the iPhone or Android app opens, it checks Expo's update service (expo.dev) for small fixes, so they arrive without a full store update. The check sends the app version, the phone's platform, a random ID made for your install and, like any internet request, your IP address. It never includes your location. See Expo's privacy policy.

Ads in the iPhone and Android apps

• The apps show one banner ad from Google AdMob. To show and measure ads and to prevent fraud, Google's software in the app collects some information from your device, such as its IP address (which gives a rough location, like your city), device and app details, an advertising identifier, and how you interact with ads. See how Google uses information from apps that use its services and Google's privacy policy.
• iPhone: the app asks Google for non-personalized ads only and never asks to track you.
• Android: ads may be personalized. You can reset or delete your advertising ID in your phone's Settings (Privacy → Ads, or Google → Ads).
• Where the law requires it (for example in the European Economic Area, the UK and Switzerland), the app asks for your choices before showing ads. You can change them any time in the app: tap i, then Ad privacy choices.
• The web app at altitude.hertzmc.com has no ads.

The website

altitude.hertzmc.com is delivered by Cloudflare, which counts page visits without cookies (Cloudflare Web Analytics). The altimeter page works out your elevation in your browser; besides that count, it only loads its own files from altitude.hertzmc.com (on Android and other non-Apple devices, a small sea-level map file that turns GPS heights into heights above sea level). It sends your location nowhere.

What Altimeter doesn't do

No accounts or sign-up. No access to your contacts, photos, camera or microphone. We don't collect any personal information ourselves, and we don't sell your information.

Who else gets data

Only Google (for the ad) and Expo (for the update check) get the data described above. We use them because their privacy commitments protect your data at least as well as this policy does.

Keeping and deleting data

• We keep nothing about you on our own servers, so there's nothing on our side to delete.
• What's saved on your phone stays until you reset the trip or uninstall the app.
• Google and Expo keep their data for as long as their own policies say (linked above). You can manage Google's ad data with the links above and, where it applies, Ad privacy choices in the app.
• To ask what data exists or to ask for anything to be deleted, email altimeter@hertzmc.com. We'll answer and help you with Google or Expo if needed.

Children

Altimeter is not directed at children under 13, and we don't knowingly collect information from them.

Changes

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

Contact

Questions? Email altimeter@hertzmc.com.