What is the ruling on working in money transfers and the legitimate ways to take a fee, and is it permissible to take a percentage of the transferred amount?

There is no harm in working in the field of financial transfers if it adheres to the Sharia regulations, the most important of which is simultaneous exchange (al-taqabud) in currency exchange; otherwise, it is not permissible. It is permissible to take a fee for the transfer, whether it is a fixed amount or a certain percentage of the transferred amount, provided that the transferred amount is known to avoid ambiguity in the fee.