Question 1

What is EPUB and why would I use it instead of PDF?

Accepted Answer

EPUB (Electronic Publication) is the standard ebook format used by Apple Books, Google Play Books, Kobo, Barnes & Noble Nook, and every mainstream ebook reader except Amazon Kindle. Unlike PDF, EPUB reflows text to fit any screen size — phones, tablets, e-ink readers — and lets users change font, font size, and theme. For books meant to be read as books, EPUB is strictly better than PDF.

Question 2

Does EPUB work on Kindle?

Accepted Answer

Yes, as of late 2022 Amazon accepts EPUB directly. You can email an EPUB file to your kindle.com address, upload it to your Kindle library via the Send to Kindle web interface, or sideload it to a Kindle device via USB. Amazon converts it to their internal format automatically. For Kindle Direct Publishing (KDP) you can upload EPUB files as the source format.

Question 3

Is the EPUB I create here valid? Will it pass EPUBCheck?

Accepted Answer

Yes. Our tool generates EPUB 3 files following the OCF (Open Container Format) specification — proper mimetype file (uncompressed, first in zip), META-INF/container.xml, OPF package document with Dublin Core metadata, navigation document (toc.xhtml), and XHTML5 chapter files. The output passes EPUBCheck, the reference validator used by Apple Books and other strict distributors.

Question 4

Can I import a Markdown file or Word document as my source?

Accepted Answer

Markdown pasting is supported — paste your full Markdown into the chapter content field and we'll convert headers, emphasis, lists, links, and code blocks to proper HTML on export. For Word documents, export to HTML from Word first (File → Save As → Web Page, Filtered), then paste the body. For large multi-chapter imports, use the 'Auto-split on heading' feature which turns each H1 in pasted content into a new chapter.

Question 5

How do I add images to my ebook?

Accepted Answer

Paste images inline as base64 data URIs in your chapter HTML, or reference them via img tags. Our export bundles any base64-encoded images automatically. Keep total image weight under 10 MB for best compatibility with older readers and email attachment limits. For a cover image, use the dedicated Cover upload — it gets special treatment in the EPUB metadata so readers display it properly.

Question 6

Why is there no ISBN field? Do I need one?

Accepted Answer

Our tool generates a UUID identifier for every ebook, which EPUB requires. If you have a real ISBN (needed for commercial retail distribution through most bookstores), you can edit the identifier field to use it in urn:isbn format. For personal use, free distribution, or publishing only through Amazon KDP, a UUID is fine and Amazon assigns its own ASIN anyway.

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