Is it permissible to complete the work on a company directory website that includes insurance, financing, and exchange companies, knowing that my task is limited to building the website and the data entry is done by the client?

The default ruling for programming is permissible (halal). However, it is forbidden to create a program known to be used for a prohibited (haram) purpose, as this constitutes aiding in sin. As for programs that can be used for both permissible and impermissible purposes, the default is permissibility, unless it is known that they will be used for something unlawful; in that case, it is not permissible to develop them. Regarding insurance and financing companies, some are Islamic, and there is no harm in dealing with them. If the developer does not know the nature of the companies that will be advertised through their programs, there is no harm in it until they learn of their impermissibility. They are not obligated to inquire about them. However, if they become aware of their illegality, then aiding them becomes forbidden, and it suffices for them to refrain from including their data.