kdp book builder

The problem

Self-published books often get rejected by Amazon KDP because of incorrect gutter margins, lack of mirrored pages, or broken Kindle navigation menus. Manual formatting in Word is tedious and error-prone, leading to "no chapter navigation" complaints from readers.

What it does

• Converts Markdown manuscripts into KDP-ready .docx files with correct trim sizes.
• Calculates gutter margins dynamically based on your total page count to prevent text from disappearing into the spine.
• Applies native Heading 1 styles to ensure Kindle devices automatically build the "Go To" navigation menu.
• Generates a clickable Table of Contents that works in both print and digital versions without broken bookmarks.
• Automates professional typesetting rules, like removing indents on the first paragraph of a new chapter or scene.

Frameworks & tools

Python, python-docx, Markdown.

Why this beats prompting it yourself

General LLM prompts often fail to handle the specific geometric requirements of physical book spines or the technical XML structure inside a .docx needed for Kindle navigation. This tool uses a deterministic script to ensure every margin, page break, and font style is technically perfect every time.

Use cases

• Formatting a fiction novel for 5.5x8.5 or 6x9 paperback distribution.
• Converting a technical manuscript into a professional Kindle ebook with a functional TOC.
• Preparing a print-on-demand interior that requires alternating (mirrored) margins for odd and even pages.
• Validating if a short-form book meets KDP's 24-page minimum or 100-page spine text requirements.

Known limitations

Requires the python-docx library and locally installed fonts. It is designed for text-heavy books rather than image-heavy coffee table books or complex layouts.