Are fireworks permissible? If not, will it be permissible to sell fireworks to non-Muslims?

Answer

Fireworks are haraam. Fireworks and the festivals associated with them are acts of satanism, tashabbuh bil kuffaar (emulating the kuffaar) and waste of money. Those who indulge in waste, according to the Qur'aan, are the "brothers of the shayaateen" (brothers of the devils). It is haraam to sell items of satanism to even non-Muslims.