Calibre

I actually don’t remember if those ancient kindles had WiFi or if you’d need to sideload stuff. At the time they were not unusable but became a lot less convenient and the writing was on the wall

I wasn’t too upset with upgrading because the device had lasted a lot of years for personal electronics and the technology had greatly improved

I know we all fans of Libby and other library sources here, but that was part of the problem. At least at my library, you have a limited number of ebooks out at once and only for two weeks each. While that doesn’t seem like a hardship, it did mean that on a vacation I’d generally need to shuffle what books I had and I couldn’t guarantee to ever be on WiFi