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EPUB vs MOBI

A side-by-side feature comparison.

Summary

EPUB is the W3C-blessed open e-book standard everyone except Amazon ships. MOBI was the Kindle format until 2022, when Amazon switched to KFX. Both are ZIP-like containers of HTML and CSS; the differences are in DRM, metadata, and which devices can render them.

Bottom line: EPUB for everyone except Kindle. Send-to-Kindle now accepts EPUB directly.

Feature comparison

Feature EPUB MOBI (Mobipocket)
Container ZIP PalmDOC + HTML
Standardized? Yes (IDPF / W3C) Proprietary (Amazon)
Devices Kobo, Nook, Apple Books, etc. Kindle (legacy)
Reflowable Yes Yes
Fixed layout Yes (EPUB 3) Limited
Status in 2026 Universal Deprecated by Amazon

About EPUB

EPUB is the open eBook standard maintained by the W3C. An .epub is a ZIP file containing XHTML documents, CSS, images, and a manifest (OPF). Reading apps render the contents like a tiny website, with reflowable text optimized for the reader's screen.

Read the full EPUB guide →

About MOBI (Mobipocket)

MOBI is the eBook format Amazon adopted when it bought Mobipocket in 2005. .mobi (and the related .azw) are PalmDB databases containing compressed HTML and embedded images. Amazon retired MOBI in favor of KFX in 2022, but the Kindle still imports .mobi files via Send-to-Kindle.

Read the full MOBI (Mobipocket) guide →

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