Today I learned about the University of Michigan Press open access ebook collection. It’s basically a catalog of free ebooks in either ePub or PDF format. According to openaccess.nl:
Open access is a broad international movement that seeks to grant free and open online access to academic information, such as publications and data. A publication is defined ‘open access’ when there are no financial, legal or technical barriers to accessing it - that is to say when anyone can read, download, copy, distribute, print, search for and search within the information, or use it in education or in any other way within the legal agreements.
I found books published as far back as 1918. The older books are PDF scans for which you won’t be able to change font size. If you are looking for free things to read, you might find something of interest on this site.