Decision brief: Build a class-booking app and try to break it

Goes with checklist version 1.0 (2026-09-26) · AI Builder Marketplace · Fill it in after your trial, then print it or save it as a PDF. It records your decision on the date below; prices and plans change after that.

Date

Decided by

What we need it for

Team size and users

Products and plans we compared

ProductPlanPrice per month, billing

Requirements

Mark each check as a must-have, a nice-to-have or not needed, then write down what you saw. Our column shows what we saw after repairs on 2026-09-26, one run per product on the free plan. Your plan and settings can give a different result.

IDCheckNeeded?Your resultOur result
T01App published
Loads at a public URL without logging in to the builder.
Our result: Emergent: failed; Lovable: passed; Replit: partly
T02Schedule
Next 14 days; Mon-Fri 07:00 and 18:30, Sat 09:00, no Sunday; 8 spots each.
Our result: Emergent: passed; Lovable: passed; Replit: passed
T03Booking
Name and email; spots left drops by one, also after a reload.
Our result: Emergent: passed; Lovable: passed; Replit: passed
T04Confirmation
Confirmation shows a unique manage link.
Our result: Emergent: passed; Lovable: passed; Replit: passed
T05Full is full
Ten simultaneous booking requests on an empty 8-spot class: 8 accepted, 2 refused. One manual double click is not this test; use simultaneous-bookings.js.
Our result: Emergent: passed; Lovable: passed; Replit: passed
T06No double booking
The same email cannot book the same class twice, also typed in capitals.
Our result: Emergent: passed; Lovable: passed; Replit: passed
T07Move
The manage link moves a booking: old class +1, new class -1.
Our result: Emergent: passed; Lovable: passed; Replit: passed
T08Cancel
The manage link cancels a booking and frees the spot.
Our result: Emergent: passed; Lovable: passed; Replit: passed
T09Manage link not guessable
The link contains a long random code, not a sequence number.
Our result: Emergent: passed; Lovable: passed; Replit: passed
T10Admin page protected
No access without or with a wrong password, in the page and through the app's own API.
Our result: Emergent: passed; Lovable: passed; Replit: passed
T11Password not exposed
The admin password is not in the page source, the JavaScript or any URL.
Our result: Emergent: passed; Lovable: passed; Replit: passed
T12Overview
The admin page lists all bookings per class, consistent with T03-T08.
Our result: Emergent: passed; Lovable: passed; Replit: passed
T13Admin cancels
The admin cancels a booking; the spot is freed and the status visible.
Our result: Emergent: passed; Lovable: passed; Replit: passed
T14CSV export
Download with exactly: class date, class time, name, email, status; rows match what you booked.
Our result: Emergent: passed; Lovable: passed; Replit: passed
T15Input checks
An empty name, a name of only spaces and an invalid email are refused by the server.
Our result: Emergent: passed; Lovable: passed; Replit: passed
T16Data survives
Bookings are still there after a reload and after republishing.
Our result: Emergent: not tested; Lovable: passed; Replit: passed
T17Usable on a phone
At 390 px wide, schedule, booking and manage link work without sideways scrolling.
Our result: Emergent: passed; Lovable: passed; Replit: passed
T18Take it with you
Export the code (GitHub or zip) and the data; try to run it outside the builder and note what does not come along.
Our result: Emergent: not tested; Lovable: passed; Replit: passed

Must-haves we could not check

A must-have you could not test is unknown, not passed. Write it down here and ask the vendor before you sign.

Costs

Yearly cost of the plan we need

One-off switching costs

Months paying for two tools

Work out switching costs, overlap and payback in Before You Renew (https://aibuildermarketplace.com/tools/renewal-check/). Leave a cost you do not know as unknown instead of guessing.

Open questions for the vendor

Decision

   

Product and plan

Main reason

Check again on (date)

What would change this decision

Our test report: https://aibuildermarketplace.com/research/one-booking-app-three-ai-builders/