Build a booking app with AI — calendars, slots, and payments

A booking app looks deceptively simple from the outside — pick a service, pick a slot, pay — but every shipped feature has an edge case that ruins the day if you skip it.

Service catalog: list services with title, description, duration, and price, plus optional deposit amount. The catalog is also where you set "must book 24 hours ahead" and similar rules; bake them in early.

Calendar and slot picker: a date picker and a list of available time slots, with conflict checks at reservation time. The conflict check is non-negotiable — without it, two customers will book the same slot and one of them will leave a one-star review.

Stripe checkout with full-pay or deposit: customers expect to pay (or pay a deposit) at booking. Skipping payment-at-booking gives you a no-show problem from week one. Stripe Checkout handles the redirect, deposit logic, and 3D Secure — do not build a custom payment form.

Confirmation, reminders, and reschedule: a confirmation screen with calendar invite, push and email reminders 24h and 1h before the appointment, and a reschedule/cancel flow with a clear policy. SMS reminders cut no-shows by ~30% — wire them via a provider hook even if you launch with email-only.

Provider side: a daily/weekly schedule view, booking detail with customer notes, and a way to block time or set business hours. Without a provider view, you are running a booking system by editing the database — fine for one provider, impossible for ten.

Three mistakes that kill booking apps within the first month of real use.

Skipping the double-booking guard. Founders implement availability as "show all slots in business hours" and check for conflicts only on the dashboard. The first time two customers tap the same slot at the same time, you owe one of them an apology and a refund. AppGenie scaffolds an availability check at reservation time — do not bypass it for "performance."

Building a custom calendar. The temptation is real: every booking app has a calendar, so it must be a competitive surface. It is not. Use a battle-tested calendar library (react-native-calendars on mobile, FullCalendar on web), and spend the time you save on the slot logic and the reminder system.

Treating the provider side as optional. A booking app with no provider view forces the operator to manage bookings via SQL or spreadsheets. That works for one provider; at three it is a part-time job; at ten it breaks. AppGenie ships a provider schedule view in the first pipeline run — keep it, even if you launch with one provider.

Traditional timeline: two to four months for a solo developer to ship the customer side, the provider side, calendar logic, Stripe payments, and the reminder system. Agency cost: $30,000 to $90,000, with the deposit/refund/cancellation policy and SMS-reminder integration usually adding the most scope creep.

With AppGenie: the service catalog, calendar/slot picker, Stripe checkout, confirmations, reminders, and provider schedule generate in the first pipeline run — typically three to five minutes for the first live preview. The output is a full Expo + React Native codebase that runs on iOS, Android, and web, with the availability check, deposit logic, and reschedule flow scaffolded from the first prompt.

What this means in practice: you spend your first week on the actual business — your services, your pricing, your cancellation policy — instead of debugging slot-conflict edge cases for a calendar UI that every booking SaaS already solved.

The ongoing cost is your AppGenie subscription plus your backend hosting, Stripe fees, and your SMS provider (Twilio or similar). No agency retainer, no per-booking SaaS markup.