Bringing your Kindle library to Shelfsort
The honest answer: Amazon doesn’t let any third-party app sync directly with your Kindle account. But there’s a workaround that takes about five minutes and lands every supported book in your Shelfsort library, properly auto-categorized.
Why this can't be automatic
Kindle is a walled garden. There’s no public API that lets a third-party tool log into your Amazon account and pull your books, and that’s by design — Amazon wants Kindle content read in Kindle apps. Anyone promising “one-click Kindle sync” is either lying or doing something Amazon will eventually shut down.
What you can do is download your books from Amazon as files and drop them into Shelfsort. Shelfsort runs Calibre on the backend and will auto-convert .azw, .azw3, .mobi, .kfx, and .kf8 into clean EPUBs, classify them, and shelve them with the rest of your library.
The four-step workaround
1Open your Amazon content page
Go to Amazon → Manage Your Content & Devices (or the same page on your country’s Amazon — .co.uk, .de, .com.au all work the same way). Sign in if it asks.
2Find “Download & Transfer via USB”
For each book, click the three-dots menu (...) → Download & Transfer via USB → pick any Kindle device from the list (any one works, even an old one) → confirm.
Your browser downloads an .azw3 file. Save them all to one folder so you can drag them in together.
3Drop them into Shelfsort
Open your library, drag the whole folder of .azw3 files onto the upload zone, and confirm when it asks “Convert these to EPUB?” (yes — that’s the magic step).
You can drop a whole folder at once — Shelfsort walks the tree and grabs every supported file.
4Wait a beat, then refresh
Calibre converts each book on the server (about 2-5 seconds per file, sometimes longer for big PDFs). When it finishes, Shelfsort runs Claude over the metadata to auto-classify the book into a fandom or shelf, and they all show up in your library.
You’re done. Your Kindle library now lives in Shelfsort alongside everything else, fully searchable and re-categorizable.
A note on DRM
Some .azw3 files Amazon serves are wrapped in DRM. Calibre will fail to convert those with an “encryption” error, and Shelfsort will put them on the Needs conversion shelf with a note. We can’t and won’t bundle DRM-removal tools into Shelfsort — that’s a legal-grey area we’d rather not dance in. If you have books like that, your best bet is to keep them in the official Kindle app for now.
Anything else?
If your books are in another ebook reader (Apple Books, Kobo, Google Play Books, etc.), the same idea applies — most of those let you export the original file, and Shelfsort accepts EPUB, PDF, MOBI, AZW, AZW3, KF8, KFX, DOCX, RTF, FB2, LIT, LRF, PDB, TXT, and HTML. Drop and go.
Have a use case this guide doesn’t cover? Email hello@shelfsort.com — a real human (the operator) reads every reply.