O&O DiskCommander is a disk space analysis tool for Windows 10, Windows 11 and Windows Server, made by the Berlin developer O&O Software. It scans drives, partitions and folders, then shows which files, folders and file types take up the space. The user can then decide what to clean up, move or keep. It is a paid program with a trial period, and it is also part of the O&O ToolBox subscription.
What a scan collects
An analysis starts by selecting a drive in the tree on the left and running Analyze. O&O DiskCommander can read internal HDDs and SSDs, USB and other removable media, network drives, OneDrive folders, VHD and VHDX virtual disks, and O&O DiskImage backup files. Scanning only reads the medium; nothing is changed unless the user later chooses a file action.
Results build up while the scan runs. A progress indicator shows the number of folders and files processed and an estimate of the remaining time. The largest files appear before the scan finishes. The user can queue several analyses for the program to process one after another.
Views of used space
Once O&O DiskCommander analyzes a drive, it splits the data into separate tabs, each answering a different question:
- Largest Files and Largest Folders list the biggest items anywhere on the drive, regardless of how deep they sit in the folder tree.
- File Types and File Categories group usage by extension and by broader categories, such as images or video.
- Tree Map draws every folder and file as a rectangle sized by the space it occupies. Hovering shows details, and double-clicking opens a folder or file.
- Overview and drive information show capacity, file counts, fragmentation and hardware details, with pie charts for a quick drive summary.
The user can sort lists by any column and filter them by name or path through a search box. The user can show them as details, tiles or icons. The tile and icon views show thumbnails for images.
Duplicate file search
The Duplicates tab looks for files with identical content. O&O DiskCommander calculates SHA1 and SHA256 hashes for comparison and can show the same hash values for integrity checks. The user can set a minimum file size, exclude folders and adjust the matching criteria. Found duplicates are marked, and deletion applies only to the files the user has marked.
Backups, virtual disks and snapshots
O&O DiskCommander opens O&O DiskImage backups and VHD or VHDX files directly, without restoring or mounting them. The user can browse the file and folder structure inside an image, check how much space its contents take, and extract individual files from it. Password-protected images prompt for the password before loading.
The program can analyze snapshot files of a drive in the same way, even when the original drive is no longer connected. This helps when examining archived disks or offline drives. The program treats images, backups and snapshots as read-only and blocks pasting files into them.
Comparing and sharing analyses
The user can save analysis results, export them and import them again later. The user can place two analyses side by side. Markers identify items that were added, deleted, changed or left unchanged between them. This makes it possible to see what grew on a drive over time or what changed after a system update. The user can export reports as CSV or text files for documentation or for passing to colleagues.
O&O DiskCommander also keeps a history of storage use and projects when a drive will run out of space if the current trend continues. An optional threshold warning reports when a drive reaches a storage limit set by the user. A detailed log records analyses and the actions taken.
Working with files
The user can open, rename, copy, move or delete files and folders found in any view within O&O DiskCommander. The user can also show them in Windows Explorer through the context menu. Deletion moves items to the Recycle Bin, and the user can configure a confirmation prompt in the settings.
Marking works across folder and partition boundaries, so the user can collect files from different locations and process them in one step. Before a paste, move or delete, the program checks whether it can actually process each marked item. It warns when it can handle only part of the selection. A separate Open Files view lists files currently locked by running processes, with the process name. The user can filter this view by drive or folder.
Interface and editions
The interface follows the Windows style and includes a dark mode. It is available in several languages, including English, German and French, and context-sensitive help opens with F1. O&O DiskCommander comes as an installable version and as a portable version. Users can buy it as a standalone license or use it as part of the O&O ToolBox subscription. A trial lets users run the full program before buying.
