How to Remove Kindle KFX DRM and Convert Kindle KFX to MOBI, EPUB, PDF, AZW3?

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As the latest Amazon Kindle format, Amazon rolled out KFX format in 2015 to take advantage of Bookerly font, and they used KFX for the standard book since then. There are around 10,000 titles on Amazon website are in KFX format. If you’re familiar with Amazon Kindle books, you must be aware that all KFX books are locked by Amazon DRM. We admit that DRM restrictions make a lot of sense in a time when piracy runs rampant. Nevertheless, if you have paid for your books, and you still cannot make the most of them due to the limitations, you might be interested in the workarounds to bypass the restrictions and liberate your Kindle books. Enjoy reading your KFX books in a cross-platform, with any reading app, or on any e-Ink Reader? Wanna share your KFX books with your friends freely? Topic in this article is primarily regarding removing KFX DRM and convert KFX to MOBI with the powerful tool - Epubor Ultimate. Of course, converting KFX to PDF/EPUB/AZW3/TXT adopts the same method.

1. The necessity of converting Kindle KFX to MOBI
2. Explanation of KFX content: files composed of a KFX eBook
3. How to remove KFX DRM and convert KFX to mobi/pdf/epub/azw3?

The necessity of converting Kindle KFX to MOBI

MOBI is the format used by the MobiPocket Reader and Amazon Kindle Readers. Technically speaking, a MOBI file is a binary database file that is built from its HTML source. MOBI formats are suited for smaller screens because of the image size limitation of 64K. Mobi files are used for storing digital books and are designed specifically for mobile devices with low bandwidth. MOBI can also display reflowable content and fixed width layout.

Nowadays most books delivered by Amazon Kindle are in KFX format which is supported by newer Kindle devices running newer firmware. However, many users still possess older Kindle devices which don't support the new KFX format. They don’t want to discard their old but working Kindle devices, so they need to convert the KFX format to MOBI, in order to make it compatible with their older Kindle eInk readers. Fortunately, we still have the option to convert KFX to KF7, a MOBI Kindle file that's optimized to be read on the older Kindle devices including the oldest Kindle eInk readers.

The table below shows the Kindle eInk readers and reading apps that support KFX format:

Kindle Devices Windows Mac iOS Android
Kindle eInk Readers and newer Fire Tablets with firmware higher than 5.8 (eg: Paperwhite 3, Voyage, Oasis, Oasis 2, Kindle Fire HD) Kindle for PC v1.19 and above,
Kindle Previewer 3
Kindle for Mac v1.19 and above,
Kindle Previewer 3
Kindle for iOS v6.03 and above (file extension must be .azw) Kindle for Android v7.2 and above (file extension must be .kfx)

Explanation of KFX content: files composed of a KFX eBook

A KFX file is not a sole eBook content file, instead, it contains the Amazon encrypted eBook content, DRM voucher, and metadata describing the book such as the author, title, categories, keywords, and the number of pages.

A complete KFX eBook downloaded via Kindle for PC/Mac higher than version 1.19 are made up of various files, see the screenshot below:


The files that make up a KFX eBook downloaded via Kindle eInk device differ from those comprised of a KFX book downloaded via Kindle for PC/Mac. Under Kindle/Documents, you’ll see a book title with .kfx extension and a folder named after the book title with .sdr extension:



Within the sdr folder, there’s a subfolder called asset, see the contents in the asset folder shown in the screenshot below:


As you can see that books in KFX format are usually composed of multiple KFX container files. The entire set of KFX files that make up the book is required for successful DRM removal and format conversion.

How to remove KFX DRM and convert KFX to mobi/pdf/epub/azw3?

Epubor Ultimate is the only tool crafted to work on Kindle KFX DRM removal directly without installing any plug-in or downgrading the version of Kindle for PC/Mac. It’s easy to operate and handle your KFX files efficiently.

To ensure the successful DRM removal and format conversion, please don’t relocate the path that stores the KFX files. You must keep the entire KFX files that make up the eBook intact. Any file or subfolder is missing will lead to failure of DRM removal or format conversion.

Step 1. Install Epubor Ultimate

Download Epubor Ultimate for free


Step 2. Run Epubor Ultimate

Once you launch Epubor Ultimate, it will detect and load your Kindle books from your Kindle eInk Reader and Kindle desktop app automatically.

Click on “eReader or “Kindle” tab, and you’ll see all your Kindle books are listed in the left side column. You can also drag and drop the KFX books to the main interface of the program. The KFX books are decrypted automatically when they’re loaded to the program.

KFX books downloaded from Kindle eInk Readers are saved in .kfx extention.


KFX books downloaded from Kindle for PC/Mac v1.19 or later are saved in .azw extension.


You can see a checkmark and "Decrypted" next to the KFX books you've removed DRM from. Click on "Decrypted", the decrypted file output folder will prompt automatically.


On the bottom part, you can choose the output conversion format, click “Convert to XXX” button, and the program starts to decrypt the books and convert the formats simultaneously. Once the conversion is done, you will see "Succeeded" at the end of the book title and you can click "Succeeded" to open the folder stored the converted ebooks.


Heads up: Please ensure the KFX books are purchased via your own Amazon account and downloaded via Kindle e-ink device or Kindle for PC/MAC installed on your computer. The books must be associated with your Amazon account. Loaned books or books obtained from other sources cannot be supported by the program.

Try Epubor Ultimate for free



Sisi is a newbie who joined Epubor in November 2017. She's a bookworm her whole life and has taken great interest in eBooks recently. She learns professional knowledge about ebooks in Epubor and loves to share her know-how to all the ebook lovers!

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