Privacy Policy

K4 Chess helps people find casual, drop-in chess games at venues and community spots in and around Zürich. The app is built to be used anonymously: there is no account, no sign-up, no email, and no personal profile. We collect as little as possible and only what is needed to make the app work.

The K4 Chess app is operated by Schachklub Kreis 4, Kalkbreitestrasse 6, 8003 Zürich, Switzerland. If you have any questions about this policy or your data, contact us at check@schachklub-k4.ch.

Because there are no accounts, we never ask for your name, email, or phone number. We do process:

• An anonymous device identifier. When you first open the app, a random, app-specific identifier is generated on your device. We store it in hashed form to power features such as your favourites, rate-limiting check-ins, and letting you manage the spots you create. It is not linked to your real identity.
• Location data. With your permission, the app uses your location to show nearby chess spots on the map and to verify that you are at a spot when you check in or create one. Your location is used for these features and is not stored as a continuous history or tied to a personal profile.
• Content you choose to submit. This includes check-in notes, an optional display name you type, meetups you create or join, community spots you add, and photos you upload to a spot. Please don't include sensitive personal information in this content, as it may be visible to other users.
• Push notification token. If you opt in to notifications, we store a push token so we can alert you to activity at spots you care about. Notifications are off by default and can be turned off at any time in the app or your device settings.
• Usage and diagnostics. We collect anonymous, aggregated usage analytics (which features are used, in-app events) and crash/error reports to keep the app working and to improve it. These are not used to identify you.

When you upload a photo to a community spot, the image is processed on our server and re-encoded, which removes embedded metadata such as EXIF location and camera information before the photo is stored. Spot photos you upload are publicly visible in the app and on public spot pages.

• To show the map, spots, presence, and meetups, and to verify check-ins.
• To send the notifications you have opted into.
• To prevent abuse (e.g. rate-limiting, handling reported content).
• To understand usage in aggregate and fix crashes so we can improve the app.

We do not sell your data, and we do not use it for third-party advertising.

We rely on a few trusted providers to run the app. They process data on our behalf and only as needed to provide their service:

• Supabase — database, storage, and backend hosting.
• Expo — delivery of push notifications.
• PostHog — anonymous product analytics.
• Sentry — crash and error reporting.
• MapTiler — map tiles and address lookup.

Some of these providers may process data on servers outside Switzerland and the EU/EEA.

Much of the app's data is short-lived by nature: check-ins expire automatically after about 90 minutes and meetups expire after their time window (around 48 hours). Content you create, such as community spots and their photos, is kept until it is removed, archived, or deleted. We retain anonymous analytics and diagnostics only as long as needed for the purposes above.

K4 Chess is not directed to children under 13, and we do not knowingly collect data from them.

You can turn notifications and location access on or off at any time in your device settings. Because the app is anonymous and not tied to an account, the simplest way to remove the local identifier and associated app data from your device is to delete the app. If you would like content you submitted (such as a spot or photo) removed, contact us at check@schachklub-k4.ch.

We may update this policy from time to time. When we do, we will revise the “Last updated” date above. Significant changes will be communicated within the app where appropriate.

Questions about this policy or your data? Email us at check@schachklub-k4.ch.