What Is EPUB Builder?
EPUB Builder creates properly structured EPUB ebook files from your text content. Add chapters, set metadata (title, author, language, cover image), and the tool packages everything into a valid EPUB 3 file that works on Kindle, Apple Books, Kobo, and other e-readers.
How to Use This Tool
Enter your book’s metadata (title, author, description), upload a cover image, then write each chapter in Markdown or paste HTML (Word's "Web Page, Filtered" export works; it is cleaned into valid XHTML). Arrange chapter order, then export the complete EPUB file. The entire build process runs in your browser — your manuscript is never uploaded to a server.
Why Use EPUB Builder?
EPUB is a structured zip format with specific XML requirements that are tedious to assemble manually. Dedicated ebook software like Calibre has a steep learning curve. This tool handles the EPUB structure automatically and gives you a standards-compliant file in minutes — free, private, and with no publishing platform lock-in. For a detailed walkthrough, see our step-by-step guide.
Frequently Asked Questions
What is EPUB and why would I use it instead of PDF?+
EPUB (Electronic Publication) is the open ebook standard, maintained by the W3C, and it is what Apple Books, Google Play Books, Kobo and Nook read. Kindle devices do not open EPUB files directly; Amazon converts an EPUB when you send it through Send to Kindle or publish it on KDP. Unlike PDF, EPUB reflows text to fit any screen and lets the reader change font, size and theme. PDF is still the better choice when the page layout itself must not change.
Does EPUB work on Kindle?+
Yes, through Amazon's conversion. Send to Kindle accepts EPUB by email to your @kindle.com address, through the Send to Kindle web page (files up to 200 MB) and from the Kindle apps; Amazon converts the book to a Kindle format before it reaches the device. Copying an .epub file to a Kindle over USB does not work, because the device cannot open EPUB. Kindle Direct Publishing accepts EPUB as an ebook manuscript, and Amazon recommends checking the conversion in Kindle Previewer.
Is the EPUB I create here valid? Will it pass EPUBCheck?+
It is built to. The file follows the EPUB 3 container rules: an uncompressed mimetype file first in the zip, META-INF/container.xml, an OPF package with Dublin Core metadata, a navigation document (toc.xhtml) and XHTML chapter files. Pasted HTML is re-serialized as well-formed XHTML, and before download the tool checks that every chapter parses and every image it uses is packaged. Our test book (Markdown chapters, a Word-style HTML chapter, an embedded image and a cover) returned 0 errors and 0 warnings in EPUBCheck 5.1.0. Run EPUBCheck yourself before submitting to a store, since unusual pasted markup can still trip it.
Can I import a Markdown file or Word document as my source?+
Paste Markdown into a chapter in Markdown mode: headings, paragraphs, bold, italic, inline code, code blocks, links, images, numbered and bulleted lists, block quotes and horizontal rules are converted on export. For Word, save as Web Page, Filtered, open the file in a browser or text editor, and paste the body into a chapter in HTML mode; the export strips Word-only tags and obsolete attributes. To split a long manuscript, paste it as Markdown and use Auto-split, which starts a new chapter at every top-level # heading. Auto-split works in Markdown mode only.
How do I add images to my ebook?+
Use Markdown image syntax, , or an img tag in HTML mode. Images given as data URIs are always included. Images given as web addresses are downloaded at export time; if a site blocks that download, the image is left out, its alt text stays in the chapter and the tool lists what was skipped. Every image is saved as a file inside the EPUB (PNG, JPEG, GIF, WebP and SVG as-is; other formats converted to JPEG), and repeated images are stored once. For the cover, use the Cover upload so readers recognize it as the book cover.
Why is there no ISBN field? Do I need one?+
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.
Which ebook readers does the EPUB output support?+
The output is a standard EPUB 3 file for Apple Books, Kobo, Google Play Books, Nook, Adobe Digital Editions, Calibre and web-based readers. For Kindle, send it through Send to Kindle or upload it to KDP, and Amazon converts it; the tool does not produce Kindle's own formats. The tool checks the file is well-formed before download but does not run a store's full ingestion checks.
Can I include images and custom fonts in the EPUB?+
Images, yes: they are packaged as files inside the EPUB. Custom fonts, no: the tool does not embed font files. The book ships a small stylesheet (a serif body face and sans-serif headings), and readers let people pick their own font anyway.
Built by Derek Giordano · Part of Ultimate Design Tools
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