since 2000
Opening an OAB File
The OAB file type is primarily associated with Outlook.
What is an OAB file?
OAB files mostly belong to Outlook by Microsoft. OAB (Offline Address Book) files are used by Outlook and Exchange to save and synchronize address book data locally. This is part of the cached mode configuration that the mail client uses.
- Usage: When running in this mode, the Exchange mailbox is synchronized to a local OST file, and the address list is synchronized to a collection of OAB files. Outlook then directly accesses the OST and OAB files on the local drive instead of communicating directly to a server. Thus, there is significantly less network communication between these two applications. By default, these files are synchronized every 8 hours, but this can be set to every 24 hours or even upon boot up if the Exchange server isn't left constantly running.
- File location: The default location of the address book files depends on the version of Windows you are running: Vista or later: "%userprofile%\AppData\Local\Microsoft\Outlook"; XP or earlier: "%userprofile%\Local Settings\Application Data\Microsoft\Outlook". The folder contains six files for a full-details offline address book or five files for a no-details offline address book.
How to open an OAB file
You need a suitable software like Outlook from Microsoft to open an OAB file. Without proper software you will receive a Windows message "How do you want to open this file?" or "Windows cannot open this file" or a similar Mac/iPhone/Android alert. If you cannot open your OAB file correctly, try to right-click or long-press the file. Then click "Open with" and choose an application. You can also display a OAB file directly in the browser:. Just drag the file onto this browser window and drop it.
Online OAB Text Viewer
or drag and drop it here
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OAB file format:
A file format defines how the data in the file is structured. The first characters in a file identify the file format, for example, HTML files start with the bytes <html>. File extension, signature and file format must match; otherwise errors will occur when the file is opened. If there are problems opening a file, you must first determine the file format used. Our analysis of the OAB files produces the following result:
An OAB file includes various formats for various programs. The two most common formats are as follows:
- 35% of all OAB files start with the bytes 20 00 00 00, which are crucial for this file format. These files are text files and can therefore be read using a text editor. The files are on average 840 KB in size and range from 3 KB to 51 MB. The file type was developed only in the last few years. The file name udetails.oab is characteristic of these files.
- 15% of all OAB files have the same signature 07 00 00 00. They consist of illegible, cryptic characters. OAB files are between 24 KB and 26 KB in size. A common filename is utmplts.oab.
All other OAB files (50%) have no consistent format. Tagged as urdndex or updndex. You can get all the details of your OAB file by dragging it onto this page or by clicking the button "Choose your .oab file to analyze" above.
Technical Data for OAB File Extension
File classification:
Data
Related links:
an oab offline address book is a special file format by Microsoft and should only be edited and saved with the appropriate software.
How to solve problems with OAB files
- Associate the OAB file extension with the correct application.
- Update your software that should actually open offline address books. Because only the current version supports the latest OAB file format. Search, therefore, e.g. on the Microsoft manufacturer website after an available Outlook update.
- To make sure that your OAB file is not corrupted or virus-infected, get the file again and scan it with Google's virustotal.com.
- Click here to open your .OAB file online - secure, fast, and no downloads needed.