DRM free list

I’m personally a fan of Kobo as it’s pretty easy to strip the DRM with a calibre plugin. (I also really like my kobo ereader)

How to make sure more of your book money goes to authors.

Ebooks.com sells DRM free books when the publishers allow it and you can set filters for that as well. The selection is good but not perfect. I supplement with the kobo store as needed. And make sure you are using calibre to manage your library :)

Older than amazon (I think?). DRM free as well and gives you all the options: https://www.baen.com/

Has a free library too: https://www.baen.com/allbooks/category/index/id/2012

I use various sources, from Kobo to bookshop.org or even finding good books from authors who give their work away for free, but I always donate at least $10-$20 for their work, like I would if I bought a paperback. Regardless, I refuse to pay for anything with DRM on it.

I'd look and see if the publisher or author sells the book directly.

I use Bookshop.org for ebooks and Libro.fm for audiobooks

https://www.betterworldbooks.com/

Better World Books is your online destination for books offering the widest selection of used and new books. We give booklovers across the world access to the power of knowledge at an affordable price and help them stay connected through reading. We better the world, one book at a time, by making a difference with every purchase made through donations and environmental programs. It's simple: Buy Books. Do Good.

Smashwords is good.