Is it permissible to work for a company that develops and programs machines for managing financial transactions, knowing that its clients include usurious banks, Islamic banks, and other companies?

It is impermissible to assist in usury in any way due to Allah's severe warning and His Messenger's, peace and blessings be upon him, cursing of its perpetrator, scribe, and witnesses. Therefore, companies assisting usurious banks by creating programs and machines is forbidden. Selling general software to anyone known to use it for usury is also forbidden.

If the company produces programs and machines for both usurious and Islamic banks, as well as oil companies, and it is possible to work for the company without participating in what is produced for usurious banks, then there is no harm in that, knowing that working for a company that does not assist in what is forbidden is more preferable.