Can I show my customers hotels where they pay at the hotel instead of paying me upfront?

Yes, you can, provided the hotel suppliers connected to your portal actually offer that kind of rate. Hotel booking APIs normally return each room rate with an indication of how it is paid, either prepaid at the time of booking or settled by the guest at the property on arrival or checkout. Once that information comes through, your portal can display it as a clear label on the room, and in many setups you can also let customers filter so they only see one kind or the other.

The practical difference matters for your cash flow. With a prepaid rate the money comes to you and you pass the booking cost on to the supplier, so your markup is collected automatically. With a pay at hotel rate the guest hands over the room cost at the desk, which means your margin is not sitting in that transaction at all. Agencies usually handle this by taking a separate service fee at the time of booking, or by treating these rates as a commissionable booking that is settled later, and how you do it depends on what your suppliers allow.

Be aware that not every supplier sells pay at hotel inventory, and some sell it only on certain properties or in certain markets. Most of these rates still need valid card details to be passed through as a guarantee, so you are not avoiding card collection entirely, and the guest may also face local taxes or resort fees at the property that were never part of what your portal showed. Cancellation rules on these rates can be stricter than people expect, so they should always be shown before the customer confirms.

The next step is to ask which of your connected hotel suppliers return pay at hotel rates, then decide how you want to collect your own margin on them before you switch the option on.