Using the MOBI UNPACK utility that I mentioned earlier, you can “unzip” a MOBI file, whatever was used to create it, as long as it’s unencrypted and regardless of whether or not the MOBI file includes its source file.

When I open April Hamilton’s book, From Concept to Community, which I purchased from Amazon in March, 2011, I get a folder named mobi7 inside of which is:

B001TOC9X2_EBOK.html
B001TOC9X2_EBOK.ncx
B001TOC9X2_EBOK.opf
images (folder)

There is no source file.


When I open one of my own books, Anyone Can Make a Kindle Book, which was created using Calibre, I get the mobi7 folder again, inside of which is:

Anyone.html
Anyone.ncx
Anyone.opf
images (folder)

Again, there is no source file.


However, when I open another of my own books, MEMOGRAMS, which was created from an EPUB file using the latest Kindlegen, I get two folders, mobi7 and mobi8, and a file named:

kindlegensrc.zip

There’s the source file, which I can further unzip if I want, and I get:

kindlegensrc (folder) in which are the files:

META-INF (folder)
mimetype
OEBPS (folder)

But I still have the two “mobi” folders to look at:

In the mobi7 folder I get:

MEMOGRAMS.html
MEMOGRAMS.ncx
MEMOGRAMS.opf
images (folder)

In the mobi8 folder I get:

MEMOGRAMS.epub
META-INF (folder)
mimetype
OEBPS (folder)


All this is to say that it is possible to “unzip” a MOBI file. It doesn’t need to include a source file to do so, and it can be done even with MOBI files created with Calibre.