Asteria

MOBI to AZW3

Turn Kindle ebook (MOBI) files into Kindle ebook (AZW3) files on your own Mac, Windows or Linux computer. Asteria is free, works offline, and never uploads your files.

How to do it

  1. Download Asteria and open it. It's free and needs no account.
  2. Drop your MOBI files onto its window, or press ⌘O (Ctrl O on Windows) to choose them. Drop as many as you like.
  3. Type convert to azw3and press Enter. AZW3 for Kindle from an e-book.
  4. The first time, Asteria asks to download Calibre, a free add-on from Kovid Goyal, under the GPL-3.0-only license. It shows the download size before you say yes, and needs no administrator password.
  5. Press ⌘↵ (Ctrl ↵ on Windows) to save. The AZW3 files appear next to the originals, which stay exactly as they were.

What it needs

MOBI to AZW3 uses Calibre, a free program for ebooks. Asteria doesn't bundle it. The first time you need it, Asteria offers to download it, checks the download against a pinned checksum, and keeps it in its own folder, where Settings can remove it again. If Calibre is already on your computer, Asteria uses that copy.

How it was tested

A real MOBI file was converted on Linux, and the AZW3 that came out was opened and checked with MOBI header to make sure it is what it says it is.

More from MOBI

More to AZW3