EPUB is the open standard for e-books — a reflowable format that adapts text and layout to fit any screen, from phones to e-ink readers. Books for screens. EPUB is supported by every major reader except, for years, the biggest one. Amazon's Kindle ecosystem long insisted on its own proprietary formats (MOBI, AZW3), turning EPUB into the format you had to convert before you could read it on the device you actually owned. That's finally changing, but the scars remain. The format itself is quietly brilliant: an EPUB is a ZIP archive containing HTML, CSS, and images — essentially a tiny website packaged as a book. For publishers and indie authors, EPUB is the format that keeps books free from any single company's walled garden.
Technical details
Full Name
Electronic Publication
MIME Type
application/epub+zip
Developer
IDPF / W3C
Magic Bytes
50 4B 03 04
Safety
.epub is a known, safe format.
What opens it
Apple Books
FREEmacOS / iOS
Calibre
FREEAll
Kobo
FREEAll
Google Play Books
FREEAll
FAQ
Can I read EPUB on Kindle?
Amazon added EPUB support to newer Kindle devices and the Kindle app. For older Kindles, use Calibre (free) to convert EPUB to MOBI or AZW3.
What is the difference between EPUB and PDF for reading?
EPUB text reflows to fit your screen — it adapts to any device and lets you change font size. PDF preserves exact page layout but doesn’t reflow, making it painful to read on small screens. For novels and text-heavy books, EPUB wins. For design-heavy documents with precise layouts, PDF is better.
What is the difference between EPUB and MOBI?
EPUB is the open industry standard supported by most e-readers. MOBI is Amazon’s older proprietary format for Kindle. EPUB supports richer formatting and is more widely compatible. Amazon now accepts EPUB directly, making MOBI largely unnecessary for new content.
How do I create an EPUB file?
Calibre (free) can convert documents to EPUB. Sigil (free) is a dedicated EPUB editor. For authors, writing in Markdown or HTML and converting with Pandoc (free) is a popular workflow. Apple Pages and Google Docs can also export directly to EPUB.