How to open .MOBI files (Kindle e-books) on Android, Windows and Linux

Q: How do I convert MOBI to EPUB?

Use Calibre: add the book, choose Convert books, and pick EPUB as the output. This works for DRM-free books only. Folders reads MOBI but doesn't convert it.

What .mobi, .azw, .azw3 and .prc files are and how to open and read DRM-free MOBI, AZW, AZW3 and PRC Kindle e-books for free on Android, Windows and Linux.

Satyam Mishra6 November 20264 min read

Cover: Folders' book reader on two phones, labelled .MOBI

Maybe you found a folder of old Kindle books on a backup drive, downloaded a free novel whose site offered “Kindle (.mobi)”, or kept .azw3 files you made in Calibre years ago. These are Amazon’s formats, and outside Amazon’s own apps very little opens them.

Folders’ book reader opens DRM-free MOBI, AZW, AZW3 and PRC files on Android, Windows and Linux, for free. Books that are still locked to an Amazon account won’t open; more on that below.

What is a .mobi file?

MOBI comes from Mobipocket, a French company whose e-book reader ran on Palm and Windows Mobile devices in the early 2000s. Amazon bought Mobipocket in 2005 and built the Kindle’s first formats on it. Under the surface, a MOBI file is a Palm Database file holding compressed HTML, which is why it shares its structure with Palm-era .prc files.

Extension	What it is
.mobi	Mobipocket e-book, the format of early Kindles and many free e-book sites
.prc	The same structure under the old Palm “resource” extension, used by Mobipocket books
.azw	Amazon’s name for its Kindle books: usually MOBI inside, often with DRM
.azw3	Kindle Format 8 (KF8), introduced in 2011 with HTML5 and CSS3 for richer layouts

Books bought from the Kindle store today mostly come in an even newer format, KFX, which isn’t one of these and is nearly always DRM-protected. MOBI itself is fading out: Amazon’s Send to Kindle service stopped accepting MOBI files and asks for EPUB instead.

How to open a .mobi file with Folders

On an Android device

Install Folders from the download section and allow file access.
Go to the folder with your books, or search for .mobi or .azw3.
Tap a book to open it in the book reader.
Received one in a chat or email? Tap it and choose Open with → Folders.

On Windows or Linux

Install Folders, open the folder of books and open a file.
On Windows, right-clicking a .mobi in File Explorer offers Open with → Folders as well, added by the installer.

What you can do with it in Folders

Table of contents and bookmarks, to jump around and mark places.
Search in book for a name or a quote.
Reading settings: text size, margins and themes such as light, sepia or dark.
Scroll or pages, and two-page spreads on wide screens.
Previous and next chapter buttons.
Your place is remembered for each book.

AZW3 books in the newer KF8 layout open too, but a complex design may come out simpler than on a Kindle.

Other ways to open .mobi files

Kindle apps and devices for books bought from Amazon, including Kindle for PC on Windows.
Calibre, free on Windows and Linux: views MOBI and AZW3 and converts DRM-free books to EPUB.
Any EPUB reader, once Calibre has converted the book.

Problems opening a .mobi file?

“This Kindle book is protected by DRM.” Books bought from the Kindle store are tied to your Amazon account and only open in Kindle apps or devices. That’s a store restriction, not a broken file. Read it in the Kindle app.
A compression Folders can’t read yet. Some MOBI and AZW3 files use a compression scheme called HUFF/CDIC, and Folders says so. If the book is DRM-free, convert it to EPUB with Calibre and open that.
Send to Kindle refuses your .mobi. Amazon no longer accepts MOBI there. Convert the book to EPUB with Calibre and send that.
The .prc isn’t a book at all. On Palm devices, .prc was also the extension of programs. A Palm program won’t open in any e-book reader.

Questions people ask

How do I open a MOBI file on Android? Install Folders and tap the file. If the book is DRM-free it opens in the reader, offline, with bookmarks and search.

How do I convert MOBI to EPUB? Use Calibre: add the book, choose Convert books, and pick EPUB as the output. This works for DRM-free books only. Folders reads MOBI but doesn’t convert it.

Can I read AZW3 files without a Kindle? Yes, if they’re DRM-free. Folders and Calibre both open them. AZW3 files bought from Amazon are usually locked and need a Kindle app.

MOBI vs AZW3 vs EPUB: what’s the difference? MOBI is the oldest and simplest. AZW3 is Amazon’s newer version with better layout. EPUB is the open standard most other stores and libraries use, and now what Amazon prefers for sending documents to a Kindle.