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You Can Now Strip DRM from Amazon’s Kindle KFX Format

When Amazon launched the newest version of its Kindle ebook format in 2015, the improved typography and hyphenation came at a price. Each KFX ebook was delivered as a collection of files with no obvious details other than unfamiliar file suffixes and a new type of DRM.

That new DRM was unbreakable, and that caused a lot of problems for those who want to protect their purchases. This problem only intensified last year when Kindle for PC gained support KFX and made it harder to download a Kindle ebook that could be deDRMed, but now we have a solution.

The latest version of the Apprentice Alf DRM-stripping tools was released last week, and it now works on KFX ebooks.

According to the blog post, this is a beta release:

This release incorporates works by several people to give initial KFX support to the plugin.  If you are not interested in removing DRM from the new Kindle KFX format, then there is no need to update at this time.  We still recommend using the older Kindle formats when possible for more successful conversion into other formats.

Install the KFX Input Plugin to automatically locate all of the files that make up a KFX format book and gather them into a KFX-ZIP.  After the DeDRM plugin removes the DRM, then the KFX Input Plugin will package it into a single KFX file.

You can download the files from Github. Bug reports should be left on the Apprentice Alf blog.


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Mike Hall April 16, 2018 um 2:57 pm

I’ve only ever used the Calibre plugin and am a little confused by this. Is this a stand alone tool or an updated Calibre plug in, because I didn’t think that Calibre could deal with DRM free KFX files (but this may just be me not bothering to read the release notes for recent versions).

As I have Kindle e-readers available I’ve always downloaded a "USB file" so I had an azw3 version of all my KFX books ready to strip the DRM for back-ups (and so never worried about KFX).

Jhowell April 16, 2018 um 3:55 pm

There was an update to the existing DeDRM plugin to handle KFX. In addition you need to install the optional KFX Input plugin, since calibre does not include KFX support directly.

fahirsch April 16, 2018 um 8:17 pm

3 weeks ago i bought a book in Amazon, downloaded it to my Mac and tried to de-drm it (I was using alf 6.5.5, the latest at the time).
Reading the FAQs (that document that nobody reads) I found the following:
"#### Macintosh
chmod -x /Applications/

Mac Note: If the chmod command fails with a permission error try again using sudo before chmod – sudo chmod […]

After restarting the Kindle program any books previously downloaded in KFX format will no longer open. You will need to remove them from your device and re-download them. All future downloads will use the older Kindle formats instead of KFX although they will continue to be placed in one individual subdirectory per book."
Had to use the sudo command and it worked.

Ivan December 28, 2018 um 12:38 am

fahirsch Greatly appreciated for that you left such a useful comment, also had problem with the book , and need to read it the PocketBook 740,now everything works fine.

Incident Report No. 38 – Unlawful Acts May 10, 2018 um 4:55 pm

[…] You Can Now Strip DRM from Amazon’s Kindle KFX Format | The Digital Reader […]

FJT December 12, 2018 um 10:12 am

KFX Input does not work. It does not gather all the necessary files.
epub works but is not free and it seems y have to buy the doc that y already bought.

Bob March 18, 2019 um 4:45 pm

None of these methods work for the newest Kindle for PC app.
I have tried these Calibre plugins and they do NOT work.
I have tried epub Ultimate software and it does NOT work either.

Bob March 18, 2019 um 4:46 pm

These Calibre plugins do NOT work.
Epub Ultimate does NOT work either.

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