File Extension OST

.OST File

File extension: OST
File type: Offline Cache
Do you have speed issues?
First check your registry for invalid entries.


Notes about the OST file extension:



Incorrect file associations could be the result of underlying issues within your PC system. As such it is highly recommended to scan your PC for invalid registry entries, unused processes and other unfavourable system settings to identify slowdown issues.

The OST file type is primarily associated with 'Exchange' by Microsoft Corporation.

Detailed information for file extension OST:


Primary association: Exchange
Company: Microsoft Corporation
Identifying characters Hex: 21 42 44 4E , ASCII: !BDN
Program ID: OSTFile , WEBFile

Other applications associated with file type OST:

  • On-Screen Takeoff (Project) by On Center Software, Inc.On-Screen Takeoff is software used in creating takeoffs from digital and paper plans.
  • Outlook (Offline Storage File) by Microsoft CorporationThe .PST file has a 2GB file size limit. When approaching the 2GB limit, if Office SP-1 is not installed, Outlook becomes extremely unstable to the point of not being able to clicking on any message, folder, etc. without locking Outlook. This includes attempting to access an .OST file. To shrink the file, delete items from their folders and then clear the Deleted Items folder using Tools | Empty Deleted Items Folder. Outlook will compress the folder in the background while the computer is idle so you may not see a size decrease immediately. The identifying characters used for this association are - Hex: 21 42 44 4E , ASCII: !BDNProgram ID: OSTFile , WEBFile Related links: MS Knowledge Base Article
  • Tivoli Storage Manager (File) by IBMThe IBM Tivoli Storage Manager family of offerings is designed to provide centralized, automated data protection that can help reduce the risks associated with data loss.
File Identifier - TrID
'Identifying characters' used on FILExt.com are
provided by Marco Pontello from his TrID database




Important: Invalid file associations could be the result of underlying issues within your Windows PC. It is highly recommended that you scan your PC for invalid registry entries, unused processes and other slowdown issues.

Technical data

To view technical data on file-extension OST click this link to expand/hide the additional area.

System Info for File Extension .OST

The following listing is compiled from the database produced by the 'Associate This!' program, selected data from the main FILExt database and information FILExt collected directly from user systems.

ProgramID: OSTFile, FileType: Office Data File

ProgramID: webfile, AppName: Dreamweaver MX

ProgramID: WEBFile, FileType: Office Data File


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