The
Leuwen University Press, in the Netherlands, is offering a big bunch of non-fiction ebooks for
free.
All of the ebooks are published in Dutch; however, the great majority of those are translated also into English.
Books published by university presses tend to be very technical and/or, and not surprisingly, academic. These books from
Leuven University Press are much more readable for the average person, than the usual fare from university presses.
The URL that I give below returns 148 ebooks.
That URL shows the ebooks that are in English. Some of the ebooks there, however, are not in English--I am assuming that those are ebooks for which no English edition is available. If all of the ebooks have Dutch titles (and you want ebooks in English), make sure that "English," and not "Nederlands," is selected at the extreme top righthand corner of the webpage.
It seems to me that mentioning that an ebook is an "open access" title is a kiss of death to some folks. However, I'll take my chances and remark that all of these ebooks are published under the open access model.
https://lup.be/collections/ro_free_ebooks.