IFilter Explorer

IFilter Explorer is a tool that shows IFilters used by various applications: Windows Search 3.0, WinFS, Exchange Server 2007, OSS 2007 Search Service, WSS v3 Search service, Windows Desktop Search 2.x, SQL Server 2005, SharePoint Portal Server 2003 and 2001, Indexing Services Model, along with Indexing Service 3.0 and 2.0.
IFilters are plugins which permit Microsoft's search engines to index various file formats, in order to make them searchable.
Wrapped up in a classical interface, the program has a large main window that's split into multiple panes designated for each supported app. Indexed information is available as long as you have any of the installed.

View, copy and save information about IFilters

Once the utility tracks down IFilters, you can check out the full path of each plugin's DLL library. For the file extensions you can find out methods used, whether or not the file types are signed, along with persistent handlers, handler names and registered addins, among other details.
It's possible to filter displayed file formats by various criteria (with IFilters only, with valid or invalid IFilters only, without any IFilters), as well as group them by extensions, file types, content types, IFilters, methods, signatures, or persistent handler names, addins, addin program ID, or just handlers.
Data from one or more selected rows can be copied to the Clipboard. Alternatively, all information can be exported to tab-delimited TXT, comma-delimited CSV or XML data files. You can also copy file names and paths, open the containing folder of a selected item, or launch a Command Prompt dialog in its location.

Evaluation and conclusion

We haven't come across any stability issues in our tests, thanks to the fact that the software tool didn't hang, crash or prompt error messages. It had minimal impact on computer performance. On the other hand, IFilter Explorer hasn't been updated for a pretty long time and doesn't work on all systems. It remained in beta development stage.