Use an eBook reader app
Open it in Calibre
Open it in Adobe Digital Editions
Open it in Apple Books
Open it in Google Play Books
Open it in Microsoft Edge
Open it in Firefox with an EPUB extension
Open it on a Kindle after converting it to a supported format
Open it on an Android or iPhone EPUB reader app
Open it in a web browser with an EPUB reader extension
Convert it to PDF if needed
Double-click the file if your device has a default EPUB app installed