How to Find Files Without Extensions
Files without extensions are surprisingly common in modern Windows file systems - application data stores, caches, exported artifacts, and files whose names were mangled in transit. Most of the time they're harmless, but they complicate file type analysis and can cause real problems during storage migrations, where handling rules often key off the extension. Windows Explorer offers no direct way to list them; FolderSizes does it with one search rule.
The One-Rule Search
- Click the Search button in the FolderSizes ribbon bar and add the drives or folders to scan on the Search Paths tab.
- On the Search Rules tab, click New Rule and select New File Rule.
- In the Name masks field, enter
*.*- then enable the "Exclude matches" option. - Click OK, then Start the search.
The trick is the inversion: *.* matches every file containing a dot in its name, so
excluding those matches leaves exactly the files with no extension. The results show
each file's full path, size, dates, and owner - across local drives, mapped drives, and UNC
paths in a single pass.
What to Do with Them
Review the results before acting - many extensionless files belong to applications that expect them exactly where they are. For genuine strays, FolderSizes supports move, copy, archive, and delete operations directly from the search results, and the list can be exported for review. Explore more advanced search capabilities, including rules based on size, dates, attributes, and owners.