Only until July!
Springer Nature, one of the greatest scientific publishers, allows downloading for free more than 400 books (approx. 8 GB) from all fields of knowledge. You can find all of them in this Excel sheet:
https://resource-cms.springernature.com/springer-cms/rest/v1/content/17858272/data/v5
These are complete books, written in English, some of them quite technical. They are in PDF (or ePub) and have no digital rights management (DRM), just a watermark outside the reading area. Thus, the books can be converted to any reading device, such as a tablet or e-book reader, using a software such as Calibre, which can convert PDF or ePub files to Amazon’s Kindle format.
How to download a book?
1: Find the book you are interested in in the excel sheet above. TIP: Use the drop down menu of the column “English Package Name” to filter by subject e.g. Behavioral Science, Biomedical and Life Sciences or Computer Science.
2: Once you found a book, follow the link in the column “OpenURL” of the excel sheet. Then click the download button.
Keep safe keep learning!
Alexgand made a python script to download them all: https://github.com/alexgand/springer_free_books