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OST Viewer is an email-viewing product developed by SysTools. The utility performs examination on email data of Exchange offline mailbox locally stored as Outlook Data File OST. OST Viewer allows examining Offline Storage Table files (OST) and cyber investigation officers can probe through emails, calendar, contacts, etc.


OST Viewer was developed and officially processed by SysTools Pvt. Ltd. Tool was officially launched and released in 2013 in the range of other email file viewing products. Software went through multiple reformation and version upgrades. Software is available online for download for further utility.

Product Overview

OST Viewer is a freeware application which is developed to read MS Exchange local cached mailbox file i.e. OST. The application is programmed with investigative and analytical prospective with outcome results suitable for forensic examination. OST File Viewer is Windows-oriented utility compatible with all versions of Windows. It also extends its compatibility towards all versions of MS Outlook reading OST files belonging to any version.


OST file reader is developed with algorithms to read file in corrupted or healthy state. Tool is GUI-based and with patent technology of adding files, displays the contents of data file added.

Independent OST Viewer

OST file viewer is a standalone utility and bids the viewing property without requiring Microsoft Outlook or Microsoft Exchange application installation. OST files belonging to various versions of Outlook can be analyzed. Except for the requirement of Windows machine to run the application, it does not obligate any application necessity further.

Preview All Data-types

Preview deliberately display all the components of OST file. It supports viewing list of email messages, address book, calendar schedules, tasks, journals, etc. separated in different indexing units. Preview of individual items is presented by tool by selecting single email item. Similarly, other data type content can be viewed individually.

Scanning Modes

Tool is integrated with algorithms supporting corrupted, orphaned and inaccessible files. It embeds two scanning modes for representing data elements viewable in OST File Viewer software. Advance Scan is available for severely corrupted OST file and for thorough potential scan and Quick Scan is for healthy state OST file.

Orphaned/Corrupted OST

Software supports orphaned/inaccessible/inoperative OST file displaying file data. It also supports OST files in damaged state because of file integrity issues, header alteration, virus intrusion, disoriented file structure, inappropriate file handling, etc. It is suggested to use Advance Scan for corrupted files; orphan files however can be scanned with Quick Scan.

View Deleted Data

An augmented facility is provided by OST file viewing tool by displaying the permanently deleted data items from the file. This gives a wider prospect to examiners or users for viewing data, which was permanently evacuated or deleted and was not readable through any other means.


Official website can be referred for information related to Licensing.


Technical support is offered through various means like emails, chat, call, ticket service, and demonstration in order to resolve technical or functioning queries.

Portable OST Viewer for Windows &Mac

Official Website