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OST to MOBI converter

Convert OST to MOBI online from any device with a free converter.

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We have already processed 5,839,765 files with total size of 9,550,355 Mbytes

About Email converter

Convert OST to MOBI files online with our free email converter app. No matter your platform — Windows 10, Mac, Android or iPhone — you can convert OST files rapidly.

Common email-related file formats include MSG, EMLX, and VCF. MSG is used by Microsoft Outlook to store individual email messages with their metadata. EMLX is a similar format used by Apple Mail for single email files. VCF (vCard) is used for storing contact information.

To change OST to MOBI, simply upload your OST file, choose a target format, and click Convert. Once done, your file will be ready to download instantly.

Check our video
OST

Outlook Offline Storage File

An OST (Outlook Offline Data File) is a file format used by Microsoft Outlook to store a synchronized copy of mailbox data locally, enabling offline access to emails, calendars, contacts, and other items. It is primarily used by Microsoft Outlook and can be accessed or converted using tools like Kernel OST to PST Converter, Stellar Converter for OST, and SysTools OST Viewer. The OST file structure is based on the Messaging Application Programming Interface (MAPI) and supports advanced features like synchronization with Exchange Server, encryption, and data compression for efficient storage and security.

MOBI

Mobipocket eBook

The MOBI (Mobipocket eBook) file format is a popular eBook format designed for digital books and documents, originally developed by Mobipocket SA and later acquired by Amazon. It is supported by various e-readers, including Amazon Kindle devices, and can be created or converted using tools like Calibre, KindleGen, and Mobipocket Creator. The format supports features like bookmarks, annotations, and DRM protection, and its structure is based on HTML, allowing for text formatting, embedded images, and hyperlinks.

Add the conversion API to your app

  • Convert over 200 file formats — including PDF, Word, Excel, HTML, images, and many more
  • Load files from disk, URLs, FTP servers, or cloud storage (such as Amazon S3 or Azure)
  • Customize output settings — rotate and reorder pages, add comments, or apply watermarks
How it works

How to convert OST to MOBI

Step 1
Click inside the file drop area to upload OST file or drag & drop OST file.
Step 2
Click on Convert button. Your OST files will be uploaded and converted to MOBI result format.
Step 3
Download link of result files will be available instantly after conversion.
Step 4
You can also send a link to the MOBI file to your email address.
FAQ

Questions & Answers

Other Supported Conversions

You can also convert OST into many other file formats. Please see the complete list below.

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