Do I get hotels from all over the world through the hotel booking API, or only in certain countries?

Yes, a hotel booking API gives you properties in most parts of the world, but the depth of that coverage is not the same everywhere, so it is worth checking your own destinations before you promise anything to a customer.

Hotel content reaches you through suppliers, and every supplier is stronger in some regions than others. A well known city will usually return a long list of properties, from international chains down to small guest houses, because several suppliers hold contracts there. A quiet town away from the main tourist routes may return only a few options, or none at all, simply because no supplier connected to your account has signed up the hotels in that place. That is not the software choosing what to show you. It depends on which suppliers are enabled on your plan and on what each of them has contracted.

Because of that, the honest way to answer whether you can sell a particular destination is to search for it rather than assume it is there. If your business is built around one region or one country, tell us which one before you go live and we can look at whether the suppliers on your plan cover it properly or whether another supplier should be added. Adding one is often possible, though it can depend on your plan and on that supplier's own terms for new agencies.

Before you start selling, run a few real searches for the cities, dates and types of property your customers ask about, and compare what comes back with what you would expect to find. That simple test will tell you more about your true coverage than any headline claim.