Popular online courses for UPSC preparation include platforms like Unacademy, BYJU'S, and Opennotes, which offer tailored courses covering various subjects like General Studies, essay-writing, and optional subjects. Many of these courses include live sessions, recorded lectures, quizzes, and doubt-clearing sessions that foster active learning. Additionally, there are mentorship programs to guide aspirants through the syllabus and exam strategy. Evaluating several course offerings to determine which aligns best with individual learning styles can maximize the effectiveness of the preparation.