BankerX Rating: ★★★★★
Vast library of resources. All authors are vetted and books are peer-reviewed, by the California State University.
Takes less than 2 minutes to sign-up for a free account. Can download up to 1,000 textbooks.
Link: bookboon.com
BankerX Rating: ★★★★★
Really high quality peer reviewed materials.
OpenStax is part of Rice University. These textbooks are used in 56% of college and universities in the U.S. and over 100 countries.
Link: openstax.org
BankerX Rating: ★★★★☆
Just under 5k open access books with over 100k citations. Aimed at scientists. Great for referencing with focus more on academic research. Less emphasis on introductory guides and basic explainers.
Link: intechopen.com
BankerX Rating: ★★★☆☆
Just under 800 textbooks available. The materials that are uploaded are great quality but there is a chance of you not finding the book you're looking for given the lack of depth across each category
Link: open.umn.edu/opentextbooks/
BankerX Rating: ★★★★★
One of the most comprehensive libraries to exist. Links to lecture materials, study guides, primers and every sub-set of a course you could think of. All linked back to established universities.
Link: textbookrevolution.org/index.php/Main…
BankerX Rating: ★☆☆☆☆
Plenty of better resources out there, would not recommend this one. Citations aren't often updated and it's not a great idea to reference from. Content quality is also a bit inconsistent.
Link: en.wikibooks.org/wiki/Wikibooks…
BankerX Rating: ★★★☆☆
Over 60k ebooks for download across textbooks, old texts, novels and academic publications. Can end up becoming a rabbit hole to find what you need. Still, a fantastic resource.
Link: gutenberg.org/wiki/Main_Page
BankerX Rating: ★★☆☆☆
Offers over 100 full length courses. Some areas are a bit thin on content especially around economics and finance. Useful for introductory level resources.
Link: saylor.org
BankerX Rating: ★★★★★
If you're really stuck on a module or just want to take up a course (at no cost), then Coursera is perfect. Learning materials are easily available to download from Ivy League universities on desktop & mobile.
Link: coursera.org