Last updated 2 August 2026
Mars Deck is a map of the solar system. It does not need to know who you are, and it mostly doesn't. This page says exactly what is collected, why, how long it is kept, and how to make us stop.
No cookies. No advertising. No tracking across other websites. Nothing is sold or shared with anyone. If your browser sends Do Not Track or Global Privacy Control, the deck records nothing at all about your visit.
The deck computes every planet, dwarf planet, asteroid and probe position on your own device, from orbital mathematics. It does not fetch positions from a server. That means the map works offline, and using it sends us nothing beyond the ordinary web request for the page.
Your location is never collected by the map. The sky view can show what is above you, and it asks first, every time, with three explicit choices — your browser's precise location, a rough lookup by IP, or typing coordinates yourself. Precise location never leaves your device. If you share a sky link with someone, it opens at their location, not yours.
One small message is sent after the page loads, to our own server at marsdeck.net. It records:
| What | Why |
|---|---|
| Page visited | To know which parts of the deck people use. |
| Referring site | To know where visitors came from. |
| Browser, OS, device type | To know what we must keep working on. |
| Time zone | A rough region, sent by your browser anyway. |
| IP address | To count unique visitors, resolve an approximate city, and block abuse. |
| Approximate city and country | To see where interest is coming from. |
The city lookup happens on our own server, against a database we host ourselves. Your IP address is not sent to any geolocation service or other third party. It is approximate — it reflects your network, not your address, and a VPN or a mobile connection will often place you somewhere else entirely.
Alongside the IP we store a one-way hash of it, salted with the current date. That is what counts you as one visitor today rather than five, and it becomes meaningless tomorrow.
You do not need one to use the map — the whole deck works signed out, forever. If you do make one, here is everything it holds.
We do not ask for your email address. An account is a callsign and a password, and there is no field for anything else. That is also why recovery codes exist: we have no way to send you a reset link, so those codes are the only door back in.
If you ever gave us an email address — nothing currently asks for one — it would be encrypted at rest. ⚠️ In plain terms that protects a stolen copy of the database, which is how data actually leaks. It does not protect against someone who has taken over the server itself, because the key lives there too. We would rather say that than imply otherwise.
Deleting your account from Account is immediate and complete: the account, the watchlist, the codes and every session go with it. There is no soft-delete and nothing is kept back.
Payment is handled entirely by PayPal. Your card details never touch this server and we never see them.
⚠️ PayPal will have an email address for you — the one on your PayPal account. That is between you and them, and it is worth saying plainly rather than leaving you to assume that "we do not ask for your email" means nobody involved has one.
What we store is the record of the purchase: the PayPal order id, the amount, the currency, and which tier it bought. That is what appears in Billing, and since we have nowhere to send a receipt, that list is your receipt. We keep it as long as the account exists, and for as long as tax law requires afterwards.
If you ask the deck a question, that question is sent to xAI's Grok model to be answered, together with figures this deck computed. Your IP is not sent to xAI. Please do not type anything private into it.
We keep a log of questions so we can see what people want the deck to do, and to meter usage. If you are signed in, the question is stored against your account so it can be shown back to you on your own dashboard — and it is deleted with your account. If you are signed out it is stored against a one-way hash of your IP, which cannot be turned back into you.
Visit records, including IP addresses, are kept for 12 months and then deleted. Aggregate counts — how many visits a page had in a month — contain nothing personal and are kept indefinitely.
Account data is kept for as long as you keep the account, and goes the moment you delete it. Purchase records outlive that, because tax law requires them to; what survives is the order id, the amount and the date, not a person.
For the map, the visit log and Ask the Deck, this rests on legitimate interest (GDPR Article 6(1)(f)): running and securing a website we publish, and understanding whether anyone is using it. We have kept the data to the minimum that serves that purpose, we do not profile anyone, and we do not combine it with anything else.
For an account and anything you buy, it rests on performance of a contract (Article 6(1)(b)) — we cannot keep a watchlist for you without storing that it is yours — and on a legal obligation (Article 6(1)(c)) for keeping the record of a payment.
If you would rather we did not, the section below is not a formality.
You can ask what we hold about you, ask for it to be corrected or deleted, or object to the collection entirely. Email hello@marsdeck.net and say so plainly — no form, no account required. Because we keep so little, "delete everything associated with my IP address" is a request we can act on immediately.
You may also complain to your national data protection authority.
Mars Deck is published by Vonfal AI / Safehouse Lab. Hosting is provided by Spaceship, in the European Union. Written contact details for the controller are available on request at the address above.
If this changes materially, the date at the top changes and the previous version stays available in the project's public repository, so there is a record rather than a quiet edit.