Built on Y Build Build this app yourself — prompt to deployed, on your own domain. Start free
BuildShipCompareThe LabAbout Start building →
Build

Build a booking app with AI in 30 minutes

Full build log: auth, calendar, payments, live.

Marcus Tan Founding Engineer, Y Build
Published Jun 12, 2026
8 min
read
cover · 1200×600

We built a real bookings app — sign-in, a calendar, a payments step, and a public page — start to finish, and logged every prompt. This is the unedited build log, not a demo.

The plan

One prompt to scaffold, one to wire auth, one to add the calendar, one to take a payment, one to deploy. Five prompts, thirty minutes, a live URL.

What tripped us up

The calendar’s timezone handling needed a second pass, and the payment webhook wanted a real domain before it would verify. Both were quick fixes once we knew to look for them.

Want the deployed version on your own domain? That’s the next note.

Liked this teardown?
Get the next experiment the day it drops. One email a week, raw numbers included.
Written by
Marcus Tan Founding Engineer, Y Build

Marcus has shipped 40+ production apps with AI tooling and runs the Build Lab experiments — the timed, reproducible head-to-heads behind every Compare and Lab note. Previously built developer platforms at two YC startups.

40+ apps shipped 8 yrs full-stack Author · The Lab
More from Marcus → @marcustan github ↗

Keep reading

All of The Lab →
Build your own app
Free · no card
Start free →