What are some e-book download sites?

You won't believe it, but just the other day I started packing for a small trip and, thinking in advance about my leisure time on the road and during long flights, I decided that audiobooks would come in handy. Reading from a screen is difficult for me, and lugging around paper copies is not an option. On the Setapp blog, where I often find useful tips for Apple users, I found the list of the best audiobook apps for both Mac and iPhone, but in the end I settled on Audible. Another pretty interesting app was Kobo, which has a wide range of audio books for purchase even without a subscription.

Why am I always so uncomfortable with free downloads of books and audiobooks? Everyone does it, I suppose, but for some reason I feel embarrassed, or I don't understand how else to explain this feeling. I wish I could find a quality audiobooks listening app on my iPhone where I could add audiobooks I've bought

https://www.gutenberg.org

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I recommend this. Features books where the US copyright has expired. Lots of classics.

Anyway, the purpose of this is more for sharing rather than seeking for answers. The above listed sites are free to download for people who'd like to pick up new skills but do not have the financial means to do so :)