Kartuin

Why we built it

Loyalty programs at cafés and warungs usually run on paper stamp cards. Customers lose them or leave them at home, and the owner has no record of who came back or which promo worked.

My co-founder Evan and I wanted a proper system for both sides. Owners get the tools to run their own marketing, and customers keep their stamps and promos in one place. I build the product; Evan handles the business side.

How it works

One visit, three connected screens.

The customer scans the QR at the counter, signs in with email, and taps to ask for a stamp. No app to download, no password.

The request appears on the cashier’s tablet. The cashier matches a 4-digit code from the customer’s phone and approves it, so stamps can’t be claimed from outside the store.

Visits, ratings and new customers land in the owner’s dashboard: who comes often, how many times, and when they last came by.

What owners control

Each card holds 4 to 20 stamps, and the owner picks the reward. Promos show on the customer’s card after check-in and are redeemed at the counter like a reward, with no messaging costs. After a stamp lands, the customer can rate the visit with one tap. Staff PINs, a tablet lock and an activity log come with every plan.

Decisions

The card follows the customer’s email instead of a piece of paper, so it can’t get lost. Everything runs in the browser, on the tablet or phone the store already has; the cashier machine stays as it is. The cashier never scans anything. The request comes to them.

Where it is

Kartuin is in pilot. Stamp cards, cashier mode and the owner dashboard are live, and the rest is changing with feedback from owners and cashiers. It’s free during the pilot.