What is the ruling on working as a programmer for a commercial company that guarantees loans to banks in exchange for an administrative fee, knowing that the company's capital comes from the banks?

Usury is a grave sin. The Prophet, peace and blessings be upon him, cursed the one who consumes it, the one who feeds it, its scribe, and its two witnesses. This indicates the prohibition of assisting in it in any way, such as guaranteeing, sponsoring, or providing a study. Since the mentioned company is based on aiding usurers, it is not permissible to work for it, as Allah Almighty says: "And do not cooperate in sin and aggression."