Preview your [DRM-free] EPUB
Here are a few free options to help preview your EPUB file.
Apple Books (aka Books and formerly known as iBooks) is a good previewer tool for your EPUB file. It is not only easy to use in terms of opening your EPUB, it is a good representative of how the file will look on an iPad and most iOS devices.
Adobe Digital Editions is an e-reader tool that allows the user to proofread their books. Keep in mind that it’s the least accurate previewer out of all three options mentioned here.
Calibre is an open-source eBook software. It’s primarily an eBook management system that can be used to create eBooks. It’s also an effective means of reviewing your book file.
Preview your [DRM-free] Kindle EPUB file
Amazon has provided a tool to preview a Kindle EPUB file.
The Kindle Previewer 3 is a free application that can be downloaded onto your laptop. It allows the user to preview how the book will look to the reader on a tablet, a Kindle e-reader or a phone. The previewer isn’t one hundred percent accurate with the varying device representations, but the application does attempt to include the most up-to-date features, like enhanced typesetting.
To preview an EPUB on a Kindle device, use the free Send-to-Kindle to upload it to your device. The file will appear in your Kindle reader app/e-reader once it’s finished uploading. This a more accurate way of previewing how the ebook file will render on a particular Kindle device.