Drop any file to identify it
No upload. No signup. No sending your file halfway across the internet.
We tell you what it is, right here in your browser.
Drop it!
Let go to identify this file.
Couldn't identify this file
Need to convert it? fwip it →
You have a .mobi file — Amazon's older e-book format that's being phased out. MOBI was the standard Kindle format for years, based on the even older Open eBook specification. It supported basic formatting but couldn't handle modern layout features. Amazon replaced it with AZW3 (KF8) for better CSS and HTML support.
MOBI had legitimate advantages in its era: small file sizes, reasonable rendering on e-ink screens, and near-universal Kindle support. But the format's limitations became increasingly obvious as readers expected better typography. Amazon now recommends submitting EPUB files for Kindle publishing — they convert to their internal format automatically. Newer Kindle devices even read EPUB directly.
Kindle devices and the Kindle app still read MOBI files. Calibre (free) opens, converts, and manages MOBI files — it can convert to EPUB, PDF, or any other e-book format. If you have a collection of MOBI files, consider converting to EPUB for broader compatibility and better formatting preservation.