Hindi is a predominant language of India.
Courses:
https://www.mindurhindi.com/how-learn-hindi-online-30-days-english-free/
(Apparently the duolingo course course is highly unreliable and contains misleading information)
Teach yourself Hindi: a unique and authentic language learning kit from the country's leading authority
Miscellaneous:
https://www.wikihow.com/Learn-Hindi
https://www.alllanguageresources.com/hindi-courses/
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Study resources
Non-Fiction-contains the necessary resources for self-learning certain languages, pre-experience not neccesary- it's being modified into a study resource hub rather than focusing on languages.