Is it permissible to increase the price of computer devices sold to a client after an agreement has been reached with him, given that the client is agreeable and satisfied?

It is permissible to sell programs or devices described by characteristics, not specifically designated, but capable of being delivered, deferred to a known term, and with their price paid in full at the contract session. This falls under the category of "Bay' al-Salam" (forward sale), which is permissible in Islamic law, as indicated by verses and hadiths.

It is permissible to offer programs and devices to those who wish to purchase them. If a person requests something and promises to buy it, it is permissible to purchase it and then sell it to them.

It is not permissible to sell specific programs or devices that are not owned by the seller at the time of the contract, as this constitutes selling what one does not own, which is forbidden in Islamic law. This is the view of the majority of jurists.