What is the ruling on working as an application programmer for a real estate company that displays real estate advertisements and contains a link and advertisements for a real estate financing website affiliated with it, which relies on conventional banks and some Islamic banks in its dealings?

Your work in programming for a company specialized in real estate is permissible because advertising real estate for sale or rent, or mediating therein, is permissible. However, if your work requires you to input information about real estate financing, the majority of whose transactions are forbidden, then this is not permissible.