Amazon’s Kindle doesn’t natively display files in the EPUB format, even though it’s one of the major ebook formats in use these days. Amazon says it can’t control EPUB’s evolution as a format so it doesn’t want to have to deal with it, and while that might make sense for the company, it doesn’t help you if you’ve got an .epub document you want to read.
You have at least three strategies, which I’ve listed below. The first will let you read an EPUB file via the web browser on your Kindle so long as you’ve got wireless access, which is a pretty neat trick. The other two options will produce a new version of the file that you can copy over to the Kindle. Note that in all three cases you’ll have to have a non-DRMed file.
Use Bookworm, the free online Epub reader from O’Reilly
Bookworm is a web-based service where you upload EPUB files to your free library, then access them through a browser. Amazingly, this actually works on the latest Kindle devices running the fancier WebKit browser, although it’s not designed for it. (I don’t have older Kindle models to test–if you do, please leave updates in the comments below.)
Bookworm points out that some EPUB files might not work because of errors made by the publisher when assembling the file, or because of bugs in the Bookworm code.
Use the free Calibre program on your PC
Calibre is still the most popular stand-alone ebook management program for all the major PC operating systems, and for good reason. It’s free, it lets you manage all of your (non-Amazon) ebook files, it can create automated news feeds to forward to your devices, and–most important for this topic–it handles all sorts of conversions, including to formats like .mobi.
Use a free online conversion website
There are several online services that offer to convert a media or text file from one format to another for free. I don’t vouch for any of the ones listed below, and I’m sure you can find several more with a Google or Bing search.
These web-based services are probably the fastest route to creating a Kindle-ready file, but you should keep in mind that there are still some drawbacks. The conversion might not work, or you might end up waiting for a converted file that never arrives. The website might also bombard you with ads, which may or may not come with their own privacy issues like tracking cookies, malware, or drive-by installations. And you’ll be making a copy of the file on a third-party website you don’t own.