FSI language courses were developed by Foreign Service Institute – U. S. Department of State using the FAST methodology (Familiarization & Short-Term Training). There is only one course of HIndi available. FSI Hindi Active Introduction covers the essentials comprehensively, and includes textbooks and audio recordings. The whole course is now in public domain, and while the textbook is easy to find on the web, the audio files are unfortunately missing. These materials are considerably old and a bit old-fashioned, without any interactive solutions or flashcards – you might even need a teacher to guide through – but they are very thorough and entirely free.