[gjsman-1000]

What's also not mentioned is that the discontinued devices don't support KFX.

KFX is the modern kindle format, AZW meanwhile is heavily PDF-based. KFX was designed ground-up by Amazon, supports every modern feature they could think of, and presumably couldn't be backported to 2013 and earlier Kindles; AZW meanwhile was basically a wrapper around a subset of PDF. KFX is a complete redo, notable enough it's what "Enhanced Typesetting" on every Kindle product page means, not a small DRM upgrade.

By doing this, all authors will soon receive guarantees that they will have the full KFX feature set when designing eBooks, and won't break AZW by accident. Trying to point this out though to the "it's about DRM" or "it's about obsolescence" crowd will get you downvoted to oblivion before the truth is even considered (speaking from experience, -4 when I dared suggest legitimate reasons exist) and is a prime example of echo chambers and deeply ingrained bias on this forum.

[WorldMaker]

The original AZW format was MOBI-based, not PDF-based. MOBI originally from a company called MobiPocket, which Amazon eventually acquired, was built to be an ePub competitor and like ePub was an HTML and JS-based solution, but in a somewhat different, proprietary DRM-friendlier container format. (ePub is "just" a ZIP file, with the DRM applied sometimes inside the container rather than outside it.)

MOBI stopped keeping up with ePub standards and standard features, in part because Amazon acquired MobiPocket. The KFX is just ePub with a new proprietary DRM container around the ZIP file that is ePub's container.

The 2013 boundary is also the "supports ePUB files directly without a conversion process" boundary in Amazon's kindle OS. It's not just useful to know for book file authors, but as a consumer it becomes useful for a quick "Can I buy a standards compliant DRM-free EPUBs such as from sites like DriveThruFiction and just send them to my Kindle with no other steps?"

[chocochunks]

No Kindle supports ePub natively. Amazon converts ePub to a supported format when you use the send to kindle email service. If you just load the book on over USB it won't work.

[WorldMaker]

Every kindle that supports the new format (Kindle devices since 2013 with latest OS upgraded) support loading non-DRM ePubs directly over USB. There's no conversion anymore. (I've done this.)

Amazon's not going to openly advertise that this deprecation is also the line in the sand where "non-DRM ePub just works", but that's what has happened.

Of course one of the sadder problems with the ePub ecosystem is that it uses the same file extension for DRM contained and non-DRM contained ePubs. At a glance it isn't easy to tell if an ePub is not DRMed. Amazon does not support any of the existing ePub DRM schemes. Their own KFX DRM is very unique and proprietary and doesn't play nice with ePub DRM "standards". You can't load DRMed ePubs over USB, those don't work. Sometimes that gives an impression still that "Amazon does not support ePubs natively", but that's the nature of DRM and how much DRM hurts the entire ebook industry in every direction.

[chocochunks]

Are you sure about that? Even Amazon's own sales page state: "Kindle Format 8 (AZW3), Kindle (AZW), TXT, PDF, unprotected MOBI, PRC natively; PDF, DOCX, DOC, HTML, EPUB, TXT, RTF, JPEG, GIF, PNG, BMP through conversion; Audible audio format (AAX). Learn more about supported file types for personal documents." implying that ePub only works through conversion. They don't support DRMed ePubs through conversion either so it's a bit odd they say that instead of including it natively.

[WorldMaker]

As I said, anecdotally I've already done it. Amazon only just enabled the PC "Send to Kindle" to support ePub directly instead of the old silly work around of rename the .epub to .kfx (and no other change). They've been very bad at keeping their list of formats up to date in their own documentation. Some of that perhaps because they don't want it to be so obvious and it is intentional obfuscation (to keep people using their store rather than going elsewhere for books), some of that because a lot of their kindle documentation seems to be in a "isn't broke, don't fix it" frozen state for years at time. You'll also note that the text you found doesn't mention "Kindle Format 10 (KFX)" at all and also you might notice that TXT and PDF are mentioned on both sides of that text as both "natively" and "through conversion" which seems to imply the original text was from the era when they were converted and they were added to the "natively" side later without remembering to clean up the other side. (They both have native support today.)

[chocochunks]

TXT and PDF are on both sides because Amazon will convert them to the appropriate Amazon format if you use send to kindle. TXT has always been natively supported on Kindle. As fair as Amazon is concerned, KFX is an internal format only for their use so there's no need to list it. When Amazon added ePub conversion officially KFX had already existed for over half a decade.

Your anecdote also seems to be the only instance of it working natively. Keep in mind Calibre will autoconvert for you.

[razorbeamz]

I was curious and just tested this with directly putting an ePub on my Kindle and it did not work.

I also tried renaming the ePub to a .kfx and it still did not work.

[fsh]

AZW is clearly not PDF based. Try opening an actual PDF on a Kindle and compare the experience.

[wafflemaker]

I had a 12y old Paperwhite 2gen and have an 11th gen one.

PDF were just not meant to be viewed on the old one, but the 11th gen handles them surprisingly well.

[Barrin92]

I don't follow the logic here. Users of old devices aren't asking for new features, they're merely asking for their devices not to be bricked. If an author wants to design against a new set of features they can do that, and that book will not be available on older hardware. Just like, if you want to build an Android app against a newer version you can do that without forcing every human being to replace their phone.

[gjsman-1000]

The old kindles can still read all previously downloaded content. Amazon's warning is literally exactly that - you can't download new books or redownload old books (i.e. AZW versions).

[monkeywork]

They are bricking the devices and not allowing them to log back into the service if they ever log out. All they had to do was not allow them to access / purchase from the store rather than keeping them from logging in.

[Barrin92]

but that has nothing to do with what you just said. How would being able to continue to download, or purchase, old books affect the ability of authors to create books to new standards going forward? It's not like me being able to still buy an ebook version made in 2015 on my device from 2012 going to interfere with you publishing a book in 2026. That's just bricking the device in case the user ever has to reset their device or has not downloaded their library.

[WorldMaker]

It complicates the Store UX, too, if they have to add "This book is/is not supported by your device" warnings to every book which also needs to know which device you are intending. With the average kindle owner often buying books directly from Amazon.com rather than the on-device Store and often having 2+ devices, they'd possibly need an exponential number of those warnings ("This book is supported by your Kindle Oasis and Kindle Paperwhite C, but not your Kindle Paperwhite B or Kindle Paperwhite A").

Also, maybe the publisher of that book in 2015 wants to upgrade to new ebook features for that book in 2026, for instance they want to add the physical book's original illustrations now that Kindle finally supports more illustrations. Does Amazon have to keep both of the 2015 and 2026 versions of the book depending on which device the user wants to use? How confused is the user when some of their devices have lovely illustrations and others don't? Should the user be able to choose to read the 2015 version of the file even on devices that support the 2026 version because they hate the book's illustrations and find them distracting?

(That gets into a larger discussion that Amazon has always preferred updating books in place on kindles with later editions as they are published, which archivists hate especially because the kindle doesn't have a great "edition version number" to rely on to track for when Amazon has delivered an update to a file, but which often consumers prefer because typos slowly disappear and books subtly become better than the last time you read them, presuming the Publisher isn't doing some drastic bait and switch and it focused only on "plussing" the book.)

[alfiedotwtf]

Unfortunately I’ve found the majority of “authors” on Amazon these days for new books are just AI slop. And I think it’s only going to get worse

[turtlesdown11]

and another thing: im not mad. please dont put in the newspaper that i got mad.