Hi Radhakrishnan, you are not alone! it’s not as easy as we’d all hope but I do have some suggestions.
Your EPUB can be freely presented on a website using Readium CloudReader
https://github.com/readium/readium-js-viewer/releases
My company’s tool MasterPlan LIVE simplifies this process and adds extra features such as offering free samples, allowing search and access control.
e.g. https://www.galdosgift.com/book-sample?mp=Client3333/Job9781999857608/002
To view an ebook on a Kindle Fire you will need to convert the EPUB to a MOBI / KF8 file.
My company’s tool CircularFLO simplifies this process for fixed layout https://www.circularflo.com or for reflowable you could try https://forums.adobe.com/thread/2169023
You can offer a direct download link to the EPUB and MOBi file from your site so customers can then open in iBooks, Google Play or maybe Adobe Digital Editions. However if you want to restrict your customer from sharing the file you will currently need to consider going through a retailer.
e.g. Kindle Direct Publishing https://kdp.amazon.com
Good luck!
Ken Jones
Circular Software
http://www.circularsoftware.com
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