Windows Explorer doesn’t have any options that group and list all the file extensions within a selected folder. As such, you can’t group file extension categories to search folders by file types contained within them. However, you can list and group all file extension categories with the Extension Indexer software.
Click the Download button on this page  to save the Extension Indexer Zip file. You can extract the Zip file by right-clicking it and selecting Extract All. Thereafter, open the software window below from the extracted folder.
Now press the Select folder to Analyze button to open a folder. The software will then group the folder’s file extensions into categories as below. It will tell you exactly how many of each file types are within the folder.
You can open the files from the window by selecting their file titles. Alternatively, to delete files select one of the categories and press the Delete selected button. To move a group of file types, press the Move selected button and select an alternative folder for them.
This software should come in handy if you need to clean folders by searching for file types. You can also quickly move a group of files to another folder with the Move selected button. Extension Indexer runs on the Windows XP, Vista and 7 platforms.