How to Remove DRM from KFX ZIP Files?

If you import Kindle KFX files directly into Calibre and they show up as KFX-ZIP in your book list, you won’t be able to open or convert them because DRM removal has failed. To back them up or read them on other devices, proper KFX DRM removal is required. This tutorial will guide you through the whole process step-by-step.

1. What is the Difference Between KFX and KFX-ZIP Files?

To understand the difference, we need to look at how Amazon package their books and how Calibre handles them:

• KFX File: KFX is Amazon's modern eBook format. A complete KFX book isn't just a single file—it is actually a bundle composed of an encrypted main container (text/layout), a metadata container, a DRM voucher, and auxiliary containers (images, fonts). These files typically have extensions like .kfx, .azw, .azw8, or .azw9.
• KFX-ZIP File: KFX-ZIP is NOT an official Amazon format. It is a temporary .zip archive created specifically by Calibre plugins or decryption scripts (like MSIXKFXArchiver) to bundle all scattered raw KFX container files together into a single package for processing.

The key differences between them depend on where you encounter the file and its DRM status:

Feature / Comparison	Standard KFX File	KFX-ZIP File
File Origin	Delivered directly by Amazon Kindle devices/apps, or generated by Calibre after DRM is removed.	Created by Calibre's KFX Input plugin or external script (e.g., MSIXKFXArchiver).
File Structure	Single unpacked KFX eBook file.	A zipped archive containing multiple raw KFX container fragments.
DRM Status (Inside Calibre)	DRM-Free (Decryption completed)	DRM Protection Intact (Decryption failed upon import)
DRM Status (Inside archived_kfx Folder)	N/A	DRM-Free Archive (Waiting to be unpacked by KFX Input plugin)
Convertibility	Can be directly converted to EPUB, PDF, etc.	Cannot be converted directly until unpacked into standard KFX format.

Summary: KFX is the actual eBook format, while KFX-ZIP is just a transitional container package used by plugins to handle multiple KFX components at once.

2. Why Do You Get a KFX-ZIP File?

There are two main scenarios where you will encounter a .kfx-zip file, depending on how you handle your Kindle books:

• Scenario 1: Generated by MSIXKFXArchiver.exe (Decrypted Package)
  When you run the MSIXKFXArchiver.exe tool (as shown in Step 4 below), it extracts raw Kindle containers, removes the DRM protection, and repacks them into a clean .kfx-zip file inside the archived_kfx folder.
  Status: DRM-Free! Simply drag this .kfx-zip file into Calibre, and the KFX Input plugin will automatically unpack it into a standard KFX book.


• Scenario 2: Directly Adding Encrypted Books to Calibre (Decryption Failed)
  If you drag raw encrypted Kindle files directly into Calibre without running external decryption scripts, the KFX Input plugin first bundles them into a temporary .kfx-zip file for the DeDRM plugin to process. If your DeDRM plugin is missing, outdated, or misconfigured, the decryption fails, and Calibre leaves the file stuck as .kfx-zip in your library list.
  Status: DRM Intact (Failed). The file remains locked and cannot be converted or opened.

Key Takeaway: If your .kfx-zip file was generated in the archived_kfx folder by running MSIXKFXArchiver.exe, it is already decrypted—just import it into Calibre! However, if it shows up as .kfx-zip inside Calibre after a direct import, your DRM removal step has failed.

3. How to Remove DRM from KFX-ZIP Files?

In Calibre, removing KFX DRM requires two plugins working together: the DeDRM plugin (for stripping DRM protection) and the KFX Input plugin (for unpacking decrypted archives into standard KFX files). Follow the detailed instructions below:

Step 1Download and Install Calibre.

Ensure you have the latest stable version of Calibre installed on your computer.

Step 2Download DeDRM Plugin and KFX Input Plugin.

Download the DeDRM plugin (v10.0.32) here and the KFX Input plugin from MobileRead repository.

Step 3Add KFX Input Plugin to Calibre.

The KFX Input plugin is required to unpack KFX-ZIP archives into standard DRM-free KFX files.

Do NOT extract the downloaded KFX Input ZIP file. Go to Calibre: Preferences > Plugins > Load plugin from file, select KFX Input.zip, click "Open", confirm with "Yes", and Restart Calibre.

Step 4Decrypt KFX Files and Save as Decrypted KFX-ZIP Archives.

Navigate to the extracted DeDRM plugin folder. Locate and double-click the MSIXKFXArchiver_xxxx.exe file (a dedicated helper tool designed for Kindle for Windows from the Microsoft Store).

This will launch a Command Prompt window and automatically decrypt your downloaded Kindle books.

Once complete, the decrypted files will be saved in a newly generated folder named archived_kfx with the .kfx-zip extension. (Note: These .kfx-zip files in this folder are already DRM-free!)

Step 5Add Decrypted KFX-ZIP Files to Calibre.

Drag the decrypted .kfx-zip files from the archived_kfx folder directly into Calibre. With the KFX Input plugin installed, Calibre will automatically unpack them and save them as clean, DRM-free KFX files.

Step 6[Optional] Convert DRM-Free KFX to EPUB / PDF.

Now that your books are in standard DRM-free KFX format, you can easily read them or convert them. Simply click "Convert books" in Calibre, choose your desired output format (EPUB, PDF, MOBI, AZW3), and click "OK".

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