For a hotel, restaurant or clinic, the booking flow is the business. And it is usually the part of the site you control least: a third-party engine in an iframe, a calendar widget, a channel manager, each able to fail without touching your web server at all.
The calendar never loads. The booking widget's own script or API fails. Your page renders perfectly around an empty rectangle.
Every date shows unavailable. A sync problem with the channel manager or PMS makes a fully open month look fully booked. Nothing errors - the engine is confidently reporting nothing available.
Book Now does nothing. The button is there, the click registers, the next step never comes.
It breaks only on mobile. The date picker works on a desktop layout and cannot be operated on the layout most of your customers are using.
A broken booking flow does not just lose you the booking. The customer books the competitor down the road, because they came ready to buy and you were the one who could not take the money.
And bookings are seasonal and spiky. A quiet Tuesday is not suspicious. Two quiet weeks in the middle of your season is a catastrophe you notice far too late.
Because the engine is usually a third party, your hosting status page and your uptime monitor are both green throughout. They are watching your server. The failure is in the widget your server rendered.
Four steps, none of which involve writing a test script.
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