title_body: Is there a eReader app for Android, Windows and Linux? Is there an eReader application that runs under Windows, Android and Linux flavors? Someone just gave me a tablet but I also use MS Windows and Linux Mint. I could wade into searching online but I presume most work under only one OS.
upvoted_answer: FBReader and Cool Reader support all the operating systems that you have listed, but I don't personally use them, so I can't give you more insights. You can try them and see if they fit your needs.