What is MOBI?

MOBI is an e-book format originally developed by Mobipocket SA, later acquired by Amazon. It was the primary format for early Kindle devices before being largely replaced by Amazon's proprietary formats (AZW, AZW3, KFX).

MOBI files support basic e-book features like reflowable text, bookmarks, and annotations. While largely superseded by newer formats, MOBI remains compatible with many e-readers and reading apps.

Legacy Format: Though older, MOBI files still work on most Kindle devices and e-reading apps.

Features

  • Reflowable text layout
  • Bookmarks and annotations
  • Basic formatting support
  • Image embedding
  • Table of contents
  • DRM support (optional)
  • Kindle compatibility
  • Smaller file sizes

Use Cases

Perfect For

  • Older Kindle devices
  • Self-publishing e-books
  • E-book distribution
  • Personal document conversion
  • Cross-platform e-reading apps

Advantages

  • Wide e-reader compatibility
  • Works on all Kindle devices
  • Simple structure
  • Good for text-heavy books
  • Smaller than PDF
  • Easy to convert from other formats

Disadvantages

  • Outdated format (replaced by AZW3/KFX)
  • Limited formatting capabilities
  • Poor multimedia support
  • Not widely supported on non-Kindle devices
  • Amazon moving away from format

Technical Information

MOBI is based on the Open eBook standard using HTML content with specific formatting.

Technical Specifications

File extension .mobi, .prc
MIME type application/x-mobipocket-ebook
Format type E-book
Content HTML-based
DRM Optional
Developer Mobipocket SA (Amazon)