Trending online resources among UPSC aspirants for study materials include platforms like Edunet, Unacademy, and Byju's, which offer comprehensive courses and study materials tailored to the UPSC syllabus. Video lectures, webinars, and interactive quizzes from these platforms assist aspirants in grasping complex topics effectively. Additionally, online forums and social media groups provide valuable exchange of tips and resources among peers. Podcasts discussing current affairs and issues relevant to the syllabus also serve as a convenient medium for on-the-go learning, further enriching preparation.