Yes, candidates who have completed a three-year diploma in engineering or technology from a recognized institution can apply for JEE Main. However, diploma holders are generally eligible for admission to engineering programs in certain institutions and may also appear for JEE Advanced if they qualify the JEE Main cutoff and meet the eligibility criteria specified by the authorities. The eligibility rules for admission to NITs and IIITs may vary, and candidates are advised to verify the latest admission requirements before applying.