Who is responsible for paying the fees of the broker when purchasing a property in Dubai?

Both.

It depends on the contract, but the normal must be between the seller and the buyer.

Dear Questioner,

Each party should pay the broker commission to its broker. If the same broker acts for both parties, then based on the parties' understanding, usually is the buyer.

The commission is 2% for each party, if the seller doesn't want to pay, the buyer should pay 4%