Availability, rates, reservations, arrivals and the bill that accumulates against a stay — with housekeeping and the front desk working from the same picture of which rooms are actually usable right now.
Talk about scopeA room is not free or occupied. It is booked, held, occupied, being cleaned, out of order, or blocked for maintenance, and the answer to "can I sell tonight" depends on all of those plus the ones arriving and leaving today. Overbooking by one room is a real cost paid at the front desk by a person, and underselling is invisible revenue lost. Everything else in a hotel system is downstream of getting that single calculation right and keeping it right while several people change it at once.
Each of these is a decision rather than a feature, and each one is expensive to change later.
A packaged product is the right answer more often than a development company usually admits, and if your problem is an ordinary one that something off the shelf already solves, we will tell you so rather than quote for it. What follows is the case for the other answer — the conditions under which building is worth what it costs.
A packaged system that mostly fits leaves a residue — the spreadsheet kept alongside it, the step done by hand every month, the field used to mean something it was not named for. When that residue is where the actual work happens, you are already maintaining custom software, just without any of the benefits of having built it.
Every business has a few processes that are genuinely its own, and those are usually the ones it competes on. Off-the-shelf software is built for the average of a sector, so it handles the ordinary parts well and the distinctive part not at all. Building is worth it exactly where that overlap fails, and rarely anywhere else.
A vulnerability in a packaged product is a vulnerability in every deployment of it, and attackers only have to find it once. A system built for one business is not on that list.