I have used this app to learn about Indian History. And this app is awesome and helped me a lot to learn Indian History, without spending a single penny. This app contains all the textbooks of NCERT from standard 1 to standard 12.
In mobile phones, it is available in epub format and in its web version it available as a flip book.
The best part is, you have complete set of ncert books in your pocket. This is really a very helpfull intiative for students, who want to study without spending money. It has support from goverment of India and is regularly update.
This is one of the must have app for students.
Thank you.