What is the religious ruling on sending digital gifts to buyers in exchange for their product review on the website, whether the review is positive or negative?

There is no objection to giving gifts to buyers in exchange for product reviews, provided that a positive review is not requested, and that the gift is given to every reviewer regardless of their evaluation. The gift is considered a reduction in price.

It is forbidden to tie the gift to a positive review only, as this encourages the buyer to lie and deceive. It is also forbidden to engage in fictitious purchases where the customer does not take the product and the price is refunded along with the gift, as this is fraud and deception.

If the digital gift is unknown, and the buyer desired the product and not the gift, there is no objection, because ignorance does not affect contracts of donation, such as a gift. However, if the purchase was made for the sake of an unknown gift, then the sale is invalid due to the possibility of gambling and the unknown gift being part of the sold item.

In summary: It is permissible if the transaction is free from fraud and gambling, whether the gift is known or unknown, and the buyer desired the product and not the gift.