I offer free shipping in my website and social media, however in the price I will add shipping price. For example I am selling a t shirt for £10 which will include £3 delivery within the price. Not sure if this is allowed. I want to do this because people from a psychological aspect would most likely buy items that has free shipping.
Wa’alaykum as Salam wa rahmatullahi wa barakatuhu,
This is permissible. You can price the item as like, and you may use the profit as you feel best. If you want to use the profit to cover shipping, then that is up to you. You may advertise it as free shipping, since everybody understands that the meaning of ‘free shipping’ is that they get the shipping for free, and someone else is bearing the cost of it.