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Kindle File Extensions (.tpz, .azw1)

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Showing 1-15 of 15 posts in this discussion
Initial post: Dec 11, 2013 12:27:55 PM PST
I am performing research on the Kindle, and I am trying to generate some content including .azw, .azw1, .azw2, and .azw3 files.

I happen to have two .azw1 files from my personal Kindle book collection, but I am having trouble finding more. I've found a few .tpz files by clicking "Send Sample Now" with deliver to: "Transfer via Computer" selected. Sometimes it downloads as a .tpz file. (example: The FBI Career Guide: Inside Information on Getting Chosen for and Succeeding in One of the Toughest, Most Prestigious Jobs in the World) Once I copy it to my Kindle, sometimes it adds a .azw1 file. Sometimes.

.azw2 seems to be solely from active content. Files downloaded to PC for Kindle seem to always be .azw. Most files delivered directly to my Kindle or "Transfer via Computer" are .azw or .azw3.

Anyone have information on how each of these extensions are generated? I'd also be interested to know if you are an Android, Blackberry, or a webOS user and what file extensions you are seeing when you deliver content directly to your device.

This information is not directly a part of my research, but your feedback may steer future research.

Posted on Dec 11, 2013 1:15:00 PM PST
Last edited by the author on Dec 11, 2013 1:16:15 PM PST
The file extensions have nothing to do with the device that the files are put on. Azw is the normal Kindle format file extension. Azw3 is also called KF8, which is a newer format, with more formatting possibilities. It is similar to epub in its capabilities. If you have found azw2 to be active content, that's fine. I've personally never heard of it, but I don't have any active content. I've never heard of azw1, either. Tpz is Topaz format, which is kind of like images of the pages, and many people hate that format, including me. I refuse to buy a Topaz book, if I can possibly help it. There was one series that I was reading that had a couple of Topaz format books right in the middle of the series, so I was forced to buy them, if I wanted to read the whole series.

ETA: I believe that no one but a few publishers have the software to produce .tpz files.

The file extensions are generated by the software used to create the file. Kindlegen usually produces azw3 or azw files, I believe. Calibre can produce either, plus the possibility of .mobi format. Mobipocket creator creates .mobi files.

Posted on Dec 11, 2013 1:36:27 PM PST
I have nothing to add except to echo Susan's comments about Topaz files. I have yet to find a single reason why any publisher would consider Topaz to be an attractive option. In addition to the legibility issues, they do not allow for font changes, strange made up characters appear in the text, the file sizes are huge and (what the heck, I'll go there again) they are sometime barely legible. All I can assume is that they are somehow derived from OCR scans which would explain some of the weird characters that the include.

Posted on Dec 11, 2013 1:47:58 PM PST
Thanks, Susan. You've been very helpful.

During my literature review, I was unable to find much mention of the .azw2 format anywhere, but it is in the user guides. Page 92:

I ask about specific devices because I was looking at the files on my old Andriod phone, and both of the Kindle books on there are .prc. I wanted to ask others about their devices since 1.) I only had two books on it and 2.) I can no longer send files to it directly since I have a new phone.

In reply to an earlier post on Dec 11, 2013 1:49:40 PM PST
Thanks, Colin!

Posted on Dec 11, 2013 2:12:51 PM PST
You didn't get a .prc file from Amazon. .prc is an older form of .mobi. It is almost identical. I think there are a few metadata differences - like some things that are in .mobi aren't in .prc, but nothing important.

Some of the public domain web sites occasionally have a .prc file.

Posted on Dec 11, 2013 2:38:04 PM PST
I can assure you that those two books were purchased from Amazon. I believe I downloaded them through the Kindle for Android application and not transfer via USB (they were downloaded onto the phone two years ago). Apparently, this needs more research.

Yes, I downloaded many .prc and .mobi files for the research from Just need to find more .azw1 files.

Posted on Dec 11, 2013 3:38:42 PM PST
Sorry, but there is no way that you got a .prc file from Amazon. I've never, ever heard of that. Check in the Manage Your Kindle page, and see if the books are there, and if so, download them again, and see what the file extension is. You might have run them through Apprentice Alf's stuff, or something, and ended up with a .prc. You can't normally move books from one device to another, due to the DRM. A few books don't have DRM, but they won't be .prc books.

Posted on Dec 11, 2013 4:59:24 PM PST
Last edited by the author on Dec 11, 2013 5:23:16 PM PST
PRC stands for "Palm Resource Compiler". As I understand it, after Amazon purchased the .mobi format from Palm, the .prc format was developed in order to open Kindle files on Palm devices. For practical purposes the formats are identical for ebooks and you can change the file extensions without any effect on the source files.

I have a lot of Kindle books purchased from non-Amazon sellers. I just checked my library and the only prc books I have are older ones from Baen Publishers.

AZW1 is just another name for TPZ. The format is identical in every respect.

Posted on Dec 11, 2013 6:24:20 PM PST
Susan, do you know of Amazon documentation that .prc's won't come from Amazon? Maybe I'm misusing the term "Amazon." I meant in general. Based on James's post, I looked at my two books, both of which are "sold by: Hachette Book Group" from 2008. So maybe that's it?

Thanks for sticking with me. I really appreciate the help, everyone.

In reply to an earlier post on Dec 11, 2013 10:29:21 PM PST
Beth Sexton says:
Marcus, the Topaz and PRC are both file types that were popular before there were Kindles.

The "Dreaded Topaz" was popular with publishers because it was almost impossible to convert to another file type. The people who purchased books disliked it for the same reason. Also, the file was based on a table of glyphs (think hieroglyphs) which made the file 5 to 10 times larger than the same book in an e-pub or mobi file. If you start reading a book and it has a funky font and OCR errors it is probably a Topaz file.

The PRC was used by Mobipocket who changed the file extension to mobi to reflect the name of their company. Amazon purchased Mobipocket in 2005.

The first Kindle was released in 2007. Amazon realized that for their e-reader to be adopted by consumer who already had e-books it would need to handle as many file types as possible.

So basically,

.prc = .mobi = azw

.tpz = azw1

.azw2 is Active Content (usually games) for e-ink Kindles

.azw3 is the new format which Amazon calls KF8 and is based on HTML5

In the early days, when Amazon had less than 100,000 books in the Kindle store, the .azw1 file format represent about 5% of the books. Almost all of them scanned from printed books. Now, it is unusual to find one unless the book is old and not very popular. Most popular ones have been replaced by an .azw version due to the complaints about "bad formatting" and "spelling errors."

IIRC the .prc format was not downloaded to a Kindle by Whispersync but they were used in early versions of the Reading Apps for phones and/or PCs (I never used either of them).

If you go back to this forum's home page and put .prc or .tpz or .azw1 in the Search Box you can read the old discussions about file formats.

In reply to an earlier post on Dec 12, 2013 8:20:51 AM PST
I don't know of any documentation on this, but I have been using Kindles since 2008, and following this and other forums assiduously, and have never heard of a .prc file coming from Amazon. It is always .azw or now, .azw3, except for active content, of course, and the occasional .tpz. They don't even send .mobi, but they support it and .prc. You could have gotten the books from Baen or perhaps Smashwords or similar sites.

In reply to an earlier post on Dec 12, 2013 8:30:37 AM PST
Bufo Calvin says:
Marcus, here is some information I put together back in 2010 that might be helpful for you (even though it is incomplete at this point)

AZW = The most common of the two formats from the Kindle store...that's the book (I think it's probably short for Amazon Whispernet)

AZW1 or TPZ = A Topaz format book (that's the other book file type will say AZW1 when delivered wirelessly, TPZ if you downloaded it with your computer first)

MBP = The "associated information" file for anything except a Topaz book (notes, highlights, and so on). MBP is MobiPocket, which Amazon now owns

TAN = The associated information file for a Topaz book (presumably, "Topaz Annotation")

PHL = Popular Highlights

APNX = The page numbers (presumably, Amazon Page Numbers X)

EA = That's the "Before you go" part at the end of the book (maybe End Addition or End Addendum...I've heard people suggest "End Advertisement", but I'd doubt that )

AZW2 = Active content (games and apps)

In reply to an earlier post on Dec 12, 2013 12:37:50 PM PST
mattnik says:
Amazon apparently uses .prc files for Android devices. I just received a Fire HDX 7 last week. I downloaded John Grisham's Sycamore Row to it and it shows up as a .prc file. I also sent it to a Samsung media player running Android. The file extension is .prc. On my PW2 and KK3 it appears as azw3. Two other books I've sent to the Fire HDX also are .prc files.

Posted on Dec 12, 2013 12:45:36 PM PST
That's weird. Since Android is based on Linux, the file extension doesn't really matter to the OS, so they should be able to call it anything they want. prc does not have the capabilities of azw3. I wonder why they would do it that way.
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Discussion in:  Kindle forum
Participants:  7
Total posts:  15
Initial post:  Dec 11, 2013
Latest post:  Dec 12, 2013

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