How to Build a Booking System: Appointments, Payments & Reminders

The four jobs a booking system must do

1. 1Show real availability — no double-bookings
2. 2Take a deposit or full payment at booking time
3. 3Send confirmation and reminders automatically
4. 4Let clients reschedule or cancel without calling you

Real-time availability engine

The hardest part is availability: combining your staff schedules, existing bookings, buffer times and time zones into an accurate slot grid. We model this with a slot generator that reads from a rules table (working hours, breaks, service duration) and subtracts confirmed bookings.

1export function openSlots(schedule: Schedule, bookings: Booking[], date: Date) {2  const slots = generateSlots(schedule, date); // 9am–6pm every 30min3  return slots.filter((slot) =>4    !bookings.some((b) => overlaps(slot, b))5  );6}

Taking deposits with Stripe

A deposit captures real intent and halves no-show rates. We use Stripe's PaymentIntent for deposits, storing the payment_intent_id on the booking row — so if the client cancels inside the refund window we can refund programmatically, outside the window the deposit is kept.

Automated reminders

A reminder sequence — 24 hours before, 2 hours before — reduces no-shows further. We send via email (Resend) and optionally SMS, triggered by a scheduled job that queries bookings starting in the next window.

Multi-staff calendars

Service businesses with multiple staff need per-staff availability, per-service durations and the ability to assign bookings to specific team members. We model each staff member as a resource with their own schedule and link bookings to both a service and a staff record.