A punch card loyalty app for a coffee shop is a small app: a digital stamp card per customer, a reward at ten stamps, and a way for staff to add a stamp that customers cannot fake, usually a staff PIN typed on the customer's phone or a code scanned at the till. Describe that to App Builder Agent and the AI agent builds it with a hosted backend so stamps survive a lost phone; you share it as an Android APK or publish it on Google Play. A first version is free; the Member plan is $1.49 per 30 days at the time of writing for unlimited builds.
Paper punch cards work, which is why every cafe has a stack of them under the counter. They also get lost, get forged with a hole punch from the stationery shop, and tell you nothing about who your regulars are. Subscription loyalty platforms fix that but charge a monthly fee per location and push your customers into their app. The middle option is an app of your own with exactly the card you would print, built by describing it.
What the app needs
- A stamp card: ten circles, filled as stamps are added, with the reward stated plainly ("10th drink free"). One card per customer, and a new card starts when a reward is redeemed.
- A way for staff to stamp that customers cannot do themselves. Two patterns work: the customer hands over the phone and a staff member types a PIN, or the till shows a rotating QR code the customer scans. Add a cooldown (no second stamp within five minutes) and a log of every stamp with time and staff PIN.
- Reward redemption: a Redeem button that also needs the staff PIN, then a fresh card. Optional: a small history ("Free flat white, 3 Sept").
- Customer identity: sign-in with a phone number or email so the card follows the customer to a new phone. A hosted backend stores customers, stamps and redemptions.
- Owner dashboard: stamps today, active customers, rewards redeemed this month, and a list of customers who have not visited in 30 days.
- A news card: one editable block on the home screen for this week's special or new opening hours.
- Shop tablet mode (optional): staff look up a customer by phone number and stamp from the counter, for customers who do not want to hand over their phone.
Leave ordering and payment out. Loyalty is a reason to come back; the reward is redeemed at the counter. If you later want pre-orders, the online store app guide and the restaurant ordering and loyalty guide cover that as a separate step.
The prompt to paste
Open App Builder Agent, sign in with Google, choose a mobile app and paste one message. Change the name, colours, reward and stamp count to yours.
Two notes. Keep the staff PINs to four to six digits and change them when someone leaves; the log tells you which PIN stamped what. If you would rather use codes than PINs, replace the stamping sentence with: "the owner screen shows a QR code that changes every 60 seconds; customers scan it from the app to receive a stamp."
What you get in the first minutes
The agent writes the screens, creates the backend tables (customers, stamps, redemptions, staff PINs, news) and shows the app in a phone preview in the browser. Sign up as a test customer, stamp with a staff PIN, try to stamp again straight away (it should refuse), fill the card, redeem, and check the owner dashboard counts it. Then describe changes:
The generated React Native code is in the editor beside the preview; you do not need to read it, but it is yours.
Getting it onto phones
Click Download APK in the preview header for an installable Android build. Put the link on a small sign at the till ("Scan for our stamp card"); customers allow installs from the browser once and tap the file. A shareable APK is fine for a single shop's regulars. For customers to find it on Google Play, ask for a signed build (signed APK and AAB with a package id like com.beanstreet.app, an auto-incrementing version code and a keystore you can back up) and follow the signed APK and AAB guide. Google Play registration is a one-time $25; personal developer accounts must run a closed test with 12 testers for 14 days before production, which your regulars can be. Builds are Android only; for iPhone customers the same project can be published as a website at a link on appbuilderagent.com, which works with the QR-code stamping pattern.
What it costs
At the time of writing the free plan includes 500K AI tokens a month (with a free APK download), with all features and no card, which covers a first version and a few rounds of changes. The Member plan is $1.49 per 30 days: 5M tokens, unlimited APK builds and source export. Pro ($5.72), Business ($31.12) and Max ($11.01) add larger token allowances for owners building more than one app. The hosted backend runs on the platform's servers. Against per-location loyalty platforms, the difference is that this card is yours: you can export the customer list and the code and delete the project whenever you like. Prices can change; the AI app builder page shows the current plans.
Notes for the US, UK and EU
A loyalty card collects a phone number or email, which is personal data. In the UK and EU (UK GDPR, GDPR) that means a short privacy notice in the app, a lawful basis (running the loyalty scheme the customer signed up for), and a way to delete an account on request; marketing notifications need the customer to opt in. In California, CCPA gives residents the right to know and delete. This is general information, not legal advice; the privacy policy guide has a template. A free-drink reward is a discount rather than a prize draw, so competition rules do not usually apply, but state the terms (one stamp per purchase, no cash value) on the card screen. Payment habits differ too: in the US and UK most customers tap a card and will happily show a phone for a stamp; in parts of the EU where cash is still common, a tablet lookup by phone number is faster than handing over a device.
Browse the shop and retail apps for card layouts and dashboard ideas, then paste the prompt with your shop's name and reward. Ten circles, one PIN, and the paper cards go in the recycling.
Frequently asked
How do staff add a stamp without customers cheating?
A staff member types a short PIN on the customer's phone, or the customer scans a code shown at the till that changes every minute. A cooldown of a few minutes per customer stops double stamps, and the backend logs every stamp with the time and the PIN used.
Does the customer need an account?
A phone number or email keeps the card when the customer changes phones, because stamps are stored in the hosted backend. A device-only card is possible but is lost with the phone, so most shops ask for a number.
Can staff stamp from the shop's tablet instead of the customer's phone?
Yes. Ask for a staff mode that looks up a customer by phone number and adds a stamp from the counter. Both patterns can live in the same app.
Can the app take orders or payments?
Keep it to stamps and rewards; the reward is redeemed at the counter. Ordering and payment are a separate project, covered by the online store and restaurant ordering guides.
What does it cost?
At the time of writing the free plan includes 500K AI tokens a month, enough to build a first version; a free APK download is included. The Member plan is $1.49 per 30 days for unlimited builds and source export. The hosted backend runs on the platform.
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