Every rejection email from KDP looked the same: "Your file contains formatting errors." No line numbers. No specifics. Just... somewhere in there, something's broken.
I spent a weekend manually opening the EPUB as a zip file, checking the XML by hand, guessing. Found it eventually-a missing ID reference in the table of contents that Word's export had silently dropped.
That's when I started keeping a list of every weird failure mode I ran into. Six months and a lot of test manuscripts later, that list turned into a tool that catches these errors before you upload anywhere-not after you get the rejection.
We're relaunching on Product Hunt today (first launch didn't go so well, long story). If you want to try it, use code PHLAUNCH for 20% off your first month.
BookKraft AI converts manuscripts into store-ready EPUB and Kindle files in minutes. It includes an EPUB validator that catches spacing and ID errors, a Kindle Format Fixer, and a cover dimension checker — all built for indie authors, no design skills needed.
Hey Product Hunt! I built BookKraftAI for authors who struggle with book formatting. Ask me anything about how it works, what platforms it supports, or how I built it.
Book Kraft AI helps authors and publishers format manuscripts professionally without hiring a designer. Upload your file, choose a template, and export a print-ready book for KDP or Ingram Spark in minutes. No design skills needed.
