Privacy

MX Shooting Calculator · in effect from 31 October 2026

What the app keeps on your device

Everything you enter: rifles, bullets, loads and velocity measurements, scopes, targets, stands, the shot log, and the calculator's settings, including the place you last looked up and your county. On a computer it is a database file in your user's app-data folder; in the browser it is the browser's storage for this site. Deleting the app's data, or the browser's data for the site, deletes it. Export backup in the menu saves a copy wherever you choose.

Card settings, including stands and named label designs with their fonts, colours, marker styles and print choices, stay on this device. They are not included in exported backups or sync copies.

Weather and your position

When you ask for the weather, the app sends the place name you typed, or your position, to Open-Meteo, which answers with the forecast. For the weather, your position is read from the device only when you press Weather here or Use my position, and only after you allow it. It is used for the weather and for today's shooting light, and is kept on your device. Open-Meteo's own terms and privacy policy cover what it does with requests.

The shot log and where you shot

When you press Log this shot, the app keeps the shot with the hold it gave, the weather, the wind and the range, and what you add: the outcome and notes. For a shot at game you can also keep where you stood and the bearing to the animal, from which the app works out where the animal stood. Your position is read from the device only when you press Mark my position (once) or Guide me there (as you walk, until you press Stop or leave the shot log), and only after you allow it; the compass only when you press Take bearing or Guide me there. While guiding, your position is only shown on the screen, not kept.

The positions you mark for your shots, and the animals' spots, are kept on your device, in your sync copy if you sync (encrypted on your device before it goes to the sync server, or in the app's own folder of your Google Drive), and in the backups you export. They are never sent anywhere else: the app shows no map and asks no map service. Copy coordinates puts them on your clipboard, to paste where you choose.

Sync with a sync key

If you turn on sync with a key, your data is encrypted on your device (XChaCha20-Poly1305, with a key made from your sync key) before it is sent to the app's sync server, which runs on Cloudflare. The server stores only that encrypted copy, under a hash of the key; it never sees the key or anything readable, and keeps no accounts or names. A copy nobody has written to for two years is removed. To keep any one sender from flooding it, the server counts the requests from each IP address over the last minute; Cloudflare does the counting, and the address is not stored or logged. Delete the synced copy in the app's Sync window removes the data at once; a note that it was deleted stays for 30 days, so your other devices stop instead of starting it again.

Sync with Google Drive

If you choose to sync through Google Drive and sign in with Google, the app asks Google for one permission: its own folder in your Drive (drive.appdata), a hidden folder only this app can see. The app keeps one file there, mxsc-sync.json, holding your rifles, bullets, loads, scopes, targets and shot log (with the positions you marked for your shots), so your devices share them. It cannot see or change any other file in your Drive, and it doesn't ask for your name or e-mail address.

The sign-in passes through the app's sync server, because Google requires a secret that can't be kept in the app. The server hands the sign-in only to the device that started it, within ten minutes, and keeps nothing afterwards: one that no device picks up is deleted within half an hour. Later it only passes requests for a fresh access token on to Google, without storing them. The sign-in is kept on your device. Your data goes straight from your device to your Drive, not through the server.

The app's use and transfer of information received from Google APIs adheres to the Google API Services User Data Policy, including the Limited Use requirements. The data is used only to sync your own records between your own devices. It is not sold, not used for advertising, not shown to anyone else, and not used to train AI models.

To stop: Stop syncing here in the app's Sync window, or Delete the synced copy to remove the file's contents from Drive too. You can also remove the app's access at myaccount.google.com/connections.

Updates on a computer

The desktop app looks for a new version only if you turn on Check for updates when the app starts in its menu (it is off until you do), or press Check now. It then downloads the latest release's update information from GitHub, where the app's releases are kept. Nothing is sent with it: GitHub sees the request and your IP address, as with any download. If you choose Update now, the app downloads the new version from GitHub too, checks that it is signed by the app's maker, and installs it.

AI assistants

The optional tool for AI assistants (MCP) runs on your own computer and reads the desktop app's database there. What you then share with an assistant is between you and its provider.

Websites and downloads

The web version and this page are hosted on GitHub Pages, and the downloads on GitHub; GitHub may log requests as described in its privacy statement. The app and these pages use no cookies, trackers or third-party scripts.

Children

The app is not directed at children.

Changes and contact

If what the app does with data changes, this page changes with it, with a new date at the top. Questions or requests: open an issue on GitHub. The app is made by David Rosendahl.