Good to know
Privacy
Stempelkaart is built to know as little as possible. A card is a random number and a count: no name, no email address, no phone number.
Who is responsible
Stempelkaart is built and run by nealvdv (nealvdv.be). For a shop's cards, that shop is the controller and nealvdv processes the data on its behalf. Send questions about this page to contact@nealvdv.be.
What we keep about a card
Per card: a random six-character card number, the number of stamps, when the last stamp was given, and the reward codes with the date they were redeemed. Per stamp: the date and whether it came through the code or the counter.
The key of your card is on your phone. We keep only an irreversible hash of it, so a leak of our database gives away no cards.
What we don't keep
No name, no email address, no phone number, no location, no purchase amounts. The card has no cookies, no ads, no analytics services and no fonts or scripts from other companies.
On your phone
Your card is kept in your browser's storage (localStorage). That is needed for your card to work without an account. If you clear your browser data, the card is gone on that device. Whether you want sound on or off and your display choices are kept the same way.
At the counter
A paired counter tablet gets one cookie: that device's key, needed to be allowed to stamp. No customer data is kept on the counter.
Against abuse
To stop the guessing of codes and the mass creation of cards, we count attempts per visitor. For that we keep a hash of your IP address, not the address itself, and we throw those counters away after seven days.
How long
A card that got no stamp for 18 months is deleted automatically, with its rewards. The history of stamps and redeemed rewards is deleted after 13 months. If a shop stops using Stempelkaart, its cards are deleted within 30 days.
Where
The website runs at Vercel and the database at Neon, two specialised hosting companies, under a data processing agreement. For both we choose a data centre in Frankfurt, in the European Union.
Your rights
You can delete your card yourself at any time: open your card and choose 'Delete this card'. Your card is then gone for good on our side too. Because we don't know who you are, we can't look up a card for you without its card number. You can always lodge a complaint with the Belgian Data Protection Authority (dataprotectionauthority.be).
Written on 3 October 2026.