Privacy Policy

Twilight doesn't track you. There's no account, no advertising, no analytics software, and no profile built about you or your device. This page explains, in full, everything the app does with data — because that list is short enough to just say plainly.

Location

Twilight uses your device's location (with your permission, via your browser's or operating system's location prompt) to calculate the Sun, Moon, and star positions, twilight times, and light-pollution estimate for where you are. Your coordinates are used as follows:

• On your device: all astronomy calculations run locally in the app — your position is never sent to a Twilight server, because Twilight doesn't operate one.
• To Open-Meteo (open-meteo.com), a weather-forecast provider: your coordinates are sent to fetch the cloud forecast used for the "Clear & Dark" observing score, and to search for places by name. Open-Meteo does not require an account or API key and is not used for any purpose beyond serving that request.

You can deny location access entirely and still use Twilight by entering a ZIP code, searching for a place by name, or typing coordinates directly.

What's stored on your device

Your preferences and your last-used location are saved locally in your browser's or app's storage, so Twilight remembers them between visits. None of this is transmitted anywhere — it never leaves your device except as described above.

• Your saved and current location
• Display preferences (12/24-hour time, red-light night mode, sky-brightness setting)
• A short-lived cache (about an hour) of the weather forecast, to avoid re-fetching it constantly
• Whether you've dismissed onboarding messages

You can clear all of this at any time by clearing your browser's site data for twilyte.info, or by deleting the app.

Anonymous visit counter

Twilight shows a running visitor count on the Console tab. Loading the page pings a small counting service; the app does not send your location, device identifiers, or any other data to it beyond what any web request inherently includes (like your IP address, which the app itself never sees or stores). The counter exists to show a running total, not to build a profile of any individual visitor.

In-app purchase (Pro features, iOS & Android app only)

The native iOS and Android apps offer an optional one-time purchase to unlock the multi-night observing planner. Purchases are processed entirely by Apple's App Store or Google Play — Twilight never receives your payment details. To verify and restore your purchase across devices, the app uses RevenueCat, which is assigned an anonymous, random identifier for your installation (not your name, email, or Apple/Google account) along with the purchase receipt Apple or Google already issued. See RevenueCat's privacy policy for how they handle that data.

What Twilight does not do

• No account, sign-in, name, or email is ever collected
• No advertising SDKs and no ad tracking
• No analytics software (no Google Analytics, no crash reporters, no session recording)
• No cookies — the app uses only local on-device storage described above
• No data is sold, shared, or used for any purpose beyond making the app work

Third-party services this app calls

Children's privacy

Twilight is a general-audience reference tool and does not knowingly collect personal information from anyone, including children. Since the app collects no personal information from any user, no age-specific handling is needed.

Changes to this policy

If what Twilight collects or how it's used changes, this page will be updated and the "last updated" date above will change accordingly.

Contact

Questions about this policy or the app can be sent via the GitHub repository.