You can explore these curated collections on the Internet Archive:
Many ancient texts are written on fragile materials like palm leaves or birch bark. Digitization creates a permanent "back up" copy for posterity. You can explore these curated collections on the
The is a non-profit digital library offering free public access to millions of books, movies, software, music, and websites. It is completely legal and safe. It hosts a massive collection of out-of-copyright or publicly shared Hindi spiritual and occult literature. You can explore these curated collections on the
I can write a detailed review—but first I’ll assume you want a review of the Internet Archive’s collection of Hindi tantra/mantra/yantra books available as free PDFs, including quality, completeness, accessibility, and legal/ethical notes. I’ll proceed on that basis. You can explore these curated collections on the