Is it permissible for me to trade in products I do not own, by displaying pictures of goods from Chinese websites at a different price, and when a customer orders, I purchase them for him and then resell them? And is it permissible for me to take the discounted amount from foreign websites for which I act as an intermediary, or must I return it to the buyer?

Selling goods that are not owned by the seller in his online store is possible in two ways: either through a salam contract, with its known conditions, where ownership of the goods at the time of the contract is not a prerequisite because they are sold described by specification (in the buyer's liability), or by promising to sell the goods, then the actual contract is concluded after the goods are purchased and enter into the seller's guarantee.

Working as a broker between buyers and owners of goods for a commission is permissible, but the reduced percentage of the goods' price goes to the buyer, not the broker, and the broker must inform the buyer of this discount. If the broker is an agent for websites selling their goods, he is not permitted to conceal the discount from the buyers and take it for himself.