NDL: is a pilot project to develop a framework of a virtual repository of learning resources with a single-window search facility. It includes educational materials ranging from primary to post-graduate level.
https://ndl.iitkgp.ac.in/

National Mission on Education through ICT and UGC initiative: A curriculum-based, interactive content in different subjects across all disciplines is being developed under this initiative.
https://epgp.inflibnet.ac.in/

NPTEL: provides E-learning through online web and video courses in Engineering, Science and Humanities streams.
https://nptel.ac.in/

SWAYAM: This is a programme initiated by Government of India. The objective of this effort is to take the best teaching learning resources to all. This platform provides all the courses, taught in classrooms from 9th class till post-graduation and it is accessed by anyone, anywhere at any time.
https://swayam.gov.in/

OAPEN: contains freely accessible academic books, mainly in the area of Humanities and Social Sciences.
https://www.oapen.org/

Open Access Library: More than 263,388 free accessible academic papers are available presently.
https://www.oalib.com/

Set of 100 Bestselling Famous Books
https://drive.google.com/drive/folders/18ez9d-8pNqhIbUAJmuPDcYmStVWb1LqV

Writings and Speeches of Dr. Babasaheb Ambedkar
https://www.mea.gov.in/books-writings-of-ambedkar.htm

Directory of Open Access Books (DOAB)
https://doabooks.org/

Open Library
https://www.oapen.org/home