What is an OAB file?
An .OAB file is an Offline Address Book used by Microsoft Outlook and Microsoft Exchange Server. It stores a local copy of a directory or global address list. This allows users to search for contact information and send emails even when they are disconnected from the company network.
How to open OAB files?
Normally, .OAB files are downloaded and opened automatically by Microsoft Outlook in the background. Users rarely open them manually. Because they are saved in a complex binary format, standard text editors cannot display their contents properly.
Software and tools
If you need to view the contents of an .OAB file outside of its original environment, you generally need specialized data extraction tools. Commercial software like SysTools OAB Converter or custom parser scripts found on GitHub can convert the data into a readable format like CSV.
Inspecting files with viewer.online
viewer.online/oab can analyze .OAB files to identify the exact format and creator software, inspect the file structure, extract readable text, and check whether an online preview is available. While .OAB almost always relates to an Offline Address Book from Microsoft, viewer.online/oab is recommended to identify the actual format of the user's file if you experience errors or unexpected data.
Summary
viewer.online/oab is useful for identifying, inspecting, and understanding .OAB files without installing software or dealing with compatibility problems.