• You can use Google Play Books to open an EPUB file on your phone.
• You can also go for a universal book reader to open the EPUB digital book on your phone/tablet/Chromebook such as PocketBook Reader (highly recommended). PocketBook Reader is a free app for reading any e-content (books, magazines, textbooks, comic books, etc.) and listening to audiobooks!.

If you already have an EPUB file on your iPhone/iPad, all you have to do is tap on the file, it will add itself to iBooks, a pre-installed app on your iPhone/iPad. Then you can click on the My Books options on your iPhone/iPad to find and read your EPUB books. 

1. Go to Send to Kindle.
2. Click 'Add to your Files'
3. Upload an ePub file.
4. Click 'Add to your Library'
5. Hit 'Send'
6. Wait for the file to process.
7. Go to the Library on your Kindle.
8. Download the book.