Can I use a free KDP ISBN?

Yes. Amazon KDP offers a free ISBN for your paperback or hardcover. If you take it:

• Leave the barcode area on your cover blank — KDP adds its own ISBN and barcode when you upload. Don't generate one in the Cover Maker, or you'll have two.
• Know that a free KDP ISBN is tied to Amazon and Amazon is listed as the publisher of record. It can't be used to publish the same book at IngramSpark or elsewhere.

Tip: In the ISBN & Barcode section, leave the ISBN field empty and keep Reserve barcode area on so the corner stays clear. If you'd like to see the reserved space on your artwork, turn on Blank white box — it prints the plain white rectangle KDP drops its barcode into.

If you want the same ISBN across KDP, IngramSpark, and other stores — and your own imprint as publisher — buy your own ISBN, enter it in the Cover Maker, and let it place the barcode. See Should I include my own barcode?