Is my work inputting data (loans, customer information, accounts, Visa cards) for a bank, using an information-saving program developed by my company, considered Haram (forbidden) in Islamic law, and is the money I receive for this work Haram or Halal (permissible)?

If the bank you work for deals in usury (riba), then your work is impermissible, based on the Almighty's saying: "And do not cooperate in sin and aggression." It is obligatory for you to refrain from this work, and the financial compensation for it is forbidden. You must leave this work and remain with the company for other permissible tasks. If you are compelled to stay in it to fulfill obligations, then there is no harm. What you received before knowing the ruling is not problematic. However, after knowing it, it is not lawful for you to possess it except out of necessity. You should take from it what you need and spend the rest on charitable causes, and do not leave it for the company.