Privacy policy

Last updated 1 November 2026

Who we are

Tell the Sky (“we”, “us”) runs the Tell the Sky website at tellthesky.com and the Tell the Sky apps for iPhone and Android. This policy explains what we collect, why, who we share it with and the choices you have. If you have a question, write to [email protected].

Your location: coarse areas only

Lanterns ride the real wind and land near real people, so the app needs a rough idea of where you are. It never needs, and we never keep, your exact position.

• Your saved area. Your account keeps one coarse area, used to offer you lanterns that drift overhead and as your default launch point. It is stored as a map cell (an H3 hexagon of about 0.1 km²), never as coordinates, and it is never shown to anyone or returned by the app to other people.
• How it is set. When you sign up, it is set once from the city your internet connection is in. Our network provider, Cloudflare, tells us that city; we do not look up or keep your IP address for this. After that, only you change it: by picking a big city from a list, or with “Use my current location”.
• “Use my current location”. If you choose this, your device asks you for permission. The apps ask only for approximate location (Android’s coarse permission, iOS’s reduced accuracy). Your device rounds its position to a map cell before anything leaves it, so the coordinates are never sent, stored or logged.
• No background tracking. The app never re-locates you in the background. It uses your location only at the moment you ask it to.
• Launch points. When you launch a lantern, the launch point is snapped to the centre of a map cell (a few square kilometres for sky lanterns, about 0.1 km² for neighbourhood lanterns) before it is saved. Your raw launch point is never stored.
• What others see. A lantern’s trail and catches show city-level labels only (for example “near Lisbon”). Nobody can see where you, the person, are.
• Visitors who are not signed in may see the map start near the city their connection is in. That is worked out for each visit and not stored.

What we collect and why

Your account

• Your email address, to sign you in and to send account emails (verifying your address, resetting your password).
• Your display name, which is shown next to the lines you write on lanterns.
• If you sign in with Google: your Google account ID, name, email address and profile picture. If you sign in with Apple: your Apple ID identifier and the email address Apple shares (which may be a private relay address).
• If you sign up with email: your password, stored only as a secure one-way hash.

What you write and do

• Lanterns you send: the message, design, altitude tier, launch cell and the lantern’s path across the sky. A lantern’s position in the sky is the lantern’s, not yours.
• Lines you add to lanterns you catch, and which lanterns were offered to you and which you caught (your logbook).
• Reports and blocks you make, so we can keep the sky safe.
• Catching settings: whether catching is on, your quiet hours, time zone, and counts of your catches.

Your messages are shared. A lantern’s message chain, with each writer’s display name, is shown to its sender and to the people who catch it. Anyone can see a lantern drifting on the map, with its design and city-level labels, but not its messages or who sent it. Please don’t put personal details in a lantern. Messages are checked automatically before they fly, and links, phone numbers, email addresses and @handles are blocked.

Sign-in and devices

• For each sign-in session: the device’s browser or app description (user agent), the IP address it signed in from, and when it expires. We use this to keep your account secure and let you sign out of devices.
• If you allow notifications in the iPhone or Android app: a push token for your device, so we can tell you when a lantern drifts over you.
• In-app notifications, such as “your lantern was caught”.

Server logs

Like any website, our servers keep short-lived technical logs (such as the time, the page requested and the connection’s IP address) to keep the service running and to stop abuse.

Cookies and storage

We use only the cookies the service needs. There are no advertising or tracking cookies.

The web app may also save small preferences, such as light or dark mode, in your browser’s local storage. They stay on your device.

Who we share it with

We never sell your data. We share it only with the services that run Tell the Sky for us, and only what each one needs:

• OVHcloud hosts our servers and database (in the United States).
• Cloudflare runs our domain and network. It handles every connection to tellthesky.com, so it sees your IP address, and it tells us the city your connection is in.
• Google provides Sign in with Google (only if you use it), Firebase Cloud Messaging to deliver push notifications to the apps, and the fonts on our pages (Google Fonts, which sees your IP address when the fonts load).
• Apple provides Sign in with Apple (only if you use it) and delivers notifications to iPhones.
• Resend sends our account emails, so it receives your email address and the email’s content.
• Fastmail hosts our support mailbox, so it holds any email you send us.
• CARTO provides the map tiles. Your browser or app loads them directly from CARTO, which sees your IP address and which part of the map you are viewing. Map data © OpenStreetMap contributors.

The wind comes from NOAA’s public Global Forecast System (GFS). Our server downloads it; nothing about you is ever sent to NOAA.

We may also disclose information if the law requires it, or to protect people from harm.

How long we keep it

• Your account, lanterns, lines, logbook, settings, reports, blocks, notifications and sign-in records are kept while your account exists, and deleted when you delete it.
• A lantern burns for up to about 14 days (longer when people catch and refuel it). When it burns out it stays in the logbooks of the people who sent and caught it.
• Email links for verifying an address or resetting a password expire quickly and are single-use. We store only a hash of each link, never the link itself.
• A sign-in session lasts 7 days. Push tokens are removed when you sign out or delete your account.
• Server logs are kept only for a short time.

Deleting your data

To delete your account, email [email protected] from the address on your account, with the subject “Delete my account”. We will confirm and delete it within 30 days. Deleting your account permanently removes:

• your account details, saved area and settings;
• every lantern you sent, and every line you wrote on other people’s lanterns;
• your logbook, catches, reports, blocks, notifications, sign-in sessions and push tokens.

You can also ask us for a copy of your data, or to correct it, at the same address. Depending on where you live (for example in the EU, UK or California) you may have further rights, such as to object to processing or to complain to your data protection authority; write to us and we will help.

Children

Tell the Sky is not meant for children under 13, and we do not knowingly collect personal data from them. If you believe a child under 13 has an account, email [email protected] and we will delete it.

Security

All connections use HTTPS. Passwords are hashed, sign-in tokens are encrypted, and access to our servers is limited. No system is perfectly secure, but we work to protect your data and will tell you if a breach affects you.

Changes to this policy

If we change this policy, we will update the date at the top of this page, and tell you in the app if the change is significant.

Contact

Questions, requests or worries about your privacy: [email protected].