Yes, diploma holders can apply for JEE Main, especially if they wish to pursue architecture programs such as B.Arch. However, for admission to B.E. or B.Tech programs in NITs, IIITs, and CFTIs through JoSAA counselling, candidates are generally required to have passed Class 12 with Physics, Chemistry, and Mathematics. Diploma holders should carefully review the eligibility criteria of the institutions they wish to apply to.