What Is a .mobi File? .mobi Format, MIME & How to Open

Quick facts

Extension.mobi

File typeMobiPocket Ebook

MIME typeapplication/x-mobipocket-ebook

CategoryDocument

Charset—

Compressible—

Format familyebook

What is .mobi

What is a .mobi file?

A .mobi file is a MobiPocket Ebook — Legacy Kindle/MobiPocket ebook format.

In the mime-db registry it maps to application/x-mobipocket-ebook. When serving .mobi over HTTP, set the Content-Type header as shown in Developer info below.

Related entities: it maps to application/x-mobipocket-ebook — and is delivered over HTTP via the Content-Type header.

How to open .mobi files

Use Calibre or Kindle to open and edit .mobi files.
Any text editor (Notepad, VS Code) can inspect the raw content as text.

Developer info

When served over HTTP, responses should set the following header:

Content-Type: application/x-mobipocket-ebook

Common software that reads/writes .mobi:

CalibreKindle

Relation chain

.mobiextension of

format

ebookserved as

mime type

application/x-mobipocket-ebooksent via header

http header

Related extensions

Related MIME types

application/x-mobipocket-ebook

.prc .mobi

Common uses

Reports and letters
Spreadsheets and budgets
Presentations
Ebooks

How to edit .mobi files

Open the file with Calibre, make your changes and save.
Most editors preserve the original formatting and encoding — avoid changing the charset.

How to create .mobi files

Create a new file and save it with the .mobi extension, or export this format from Calibre.

Frequently asked questions

What programs can open .mobi files?

Common options include Calibre, Kindle. You can also open many of these files with built-in viewers or a browser.

How do I create a .mobi file?

Create a new file in any text editor or the app that owns the format and save it with the .mobi extension.

What is the relationship between .mobi and the application/x-mobipocket-ebook MIME type?

application/x-mobipocket-ebook is the media type identifier used for .mobi files during network transfer (for example in the HTTP Content-Type header).

Sources & standards

Updated 2026-09-13

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