Top online coaching institutes for UPSC preparation include Raj IAS, known for its quality faculty and comprehensive study material, and Insights IAS, which offers a variety of resources including test series and strategy workshops. Unacademy stands out for its extensive video lectures and interactive quiz sessions. Additionally, Vision IAS is popular for its current affairs coverage and mains answer writing practice. Each of these institutes has a unique approach, catering to different learning preferences, making them reliable options for aspirants.