The use of conventional credit cards is permissible as long as there is no generation of interest. Muslims should try their best to encourage conventional credit cards issued by Muslim institutions in order to be away from interest dealings.
Dr. Monzer Kahf, a scholar in Islamic economics and a financial expert, states the following: Using conventional credit cards and signing their contracts is permissible if you know for sure that you will not allow any interest to generate. The reason is that credit cards give you a choice to generate interest or not. If you know that you are not going to withdraw cash or delay payment till after the grace period, it is then permissible to use a credit card. However, having an interest condition in the card contract makes it haram to be issued by Muslims and banks in the Muslim countries. This implies that Muslims should make as much effort as they can not to encourage conventional credit cards issued by Muslim institutions and companies.
Selling conventional credit cards, knowing that the majority of purchasers use it for interest, is certainly not permissible because it amounts to selling interest loans.