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
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