Hello Sandhya,

Cracking IIT or NIT without coaching for or college is not impossible but in the same way not a very easy task as you have asked you can also study through YouTube and follow a good study material to score well in IIT JEE entrance examination that is whether it be JEE mains or JEE advanced but it depends on the channel which you prefer whether it be YouTube or study material my suggestion is to prefer coaching or a good college because how hard working you are or how dedicated you are it doesn't matter the only thing that matters is experience all the faculty who teach you.

When you join a coaching centre or any good college the faculty who guide you you have been teaching in the same field since years so they have a good experience in guiding you what to read and what not to read and how to score maximum possible marks in the jee entrance examinations.

Still studying through YouTube channels and study materials is not a very bad idea but if you think you can do it then you can research and select some good YouTube channels and study materials and start your preparation and be very dedicated and positive minded all the time.