For the most part Amazon’s Kindle has cornered the eBook market, making itself the generic version of a universal platform. But fear not, if you don’t have a Kindle, don’t want to download their app, don’t want to support them and/or don’t want to hand over your £££ to Bezos there are alternatives.
.epub
The main, general use eBook format is .epub files and while I’ve done a criminally negligent amount of research on the subject I do use an app called ReadEra myself. It’s free and it does the job.
.mobi
If you do use Amazon’s platform then that’s fine too, all of my books that I sell on this site come as .mobi files too – which is Amazon’s proprietary format. If you leave their ‘ecosystem’ though you do have to take some extra steps to read them though. If you want to do that then you can check out their own help page here.
PDFs are PDFs, I don’t currently offer them because they tend not to be great for reading on mobile devices. If you want them then hit me up, if enough people say yes I’ll add them, otherwise I can sort something for you directly.