How to use
Drop a folder or press “Choose folder”. To inspect only what is inside a ZIP, use “Analyze a ZIP” (nothing is unpacked).
In the “Space map” treemap, larger rectangles take more space. Hover to see details. Click a folder to go inside and use the breadcrumb above to go back.
With a screen reader or the keyboard, switch to “Table”. The same folder is shown as a table sorted by size.
Under “Reports”, switch between kind, extension, largest files, largest folders, old files, empty folders and duplicate candidates.
Under “Export”, save all reports in one Excel file, or the selected report as CSV. The treemap can also be saved as a PNG.
What it does
A treemap where area is size
The squarified algorithm keeps area proportional to size while keeping the rectangles as close to squares as it can. Click a folder to go inside and use the breadcrumb to go back. When one folder has a huge number of files, the 149 largest are drawn and the rest are merged into “N more items”.
Seven kinds, shown by color
Images, video, audio, documents, archives, code and other get one color each, with the legend and percentages also written as text. The kind comes from the extension, and the browser’s MIME type is used only when the extension does not decide it.
Handles hundreds of thousands of files
Up to 300,000 files can be loaded. Contents are not read: only names, sizes and modified times. The folder tree is built in slices that hand control back to the page, so it stays responsive while loading.
Readable as a table, usable by keyboard
Every drawn rectangle is a button whose label has the name, size and share (rectangles too small to draw are counted and listed in the table). Switch to “Table” to see the same folder as a table sorted by size. On a phone, the first tap shows details and the second tap opens the folder.
Reports for cleaning up
Totals and shares by kind and extension, largest files, largest folders, files not modified for 1 to 10 years, the count of zero-byte files, empty folders and same-name-and-size duplicate candidates (with the space they might save). You can show 10 to 500 rows.
Excel and CSV that cannot run formulas
Excel has one sheet per report with a frozen header and autofilter, and sizes as numbers. In CSV a name or path starting with = + - or @ gets a leading ' so a spreadsheet will not execute it.
Use cases
- Find which folders and kinds of files are largest when a PC or file server runs low on space
- Check a project folder for big videos or leftover backups before delivering or archiving it
- List files that have not been modified for years as candidates for cleanup
- Get a first idea of whether files with the same name and size exist in several folders
- Share a per-folder or per-extension size table with a team as an Excel sheet
Supported formats
Input
Output
Capability matrix
| Feature | Support | Notes |
|---|---|---|
| Space analysis of a dropped or chosen folder (with subfolders) | Supported | Up to 300,000 files. Contents are not read; names, sizes and modified times are used |
| Treemap (click to drill down, breadcrumb to go back) and a table alternative | Supported | Up to 150 rectangles per folder; the rest are merged into “more” |
| Space inside a ZIP | Supported | Reads uncompressed and compressed sizes from the directory; nothing is unpacked. ZIP only |
| Totals by extension and kind, largest files, largest folders | Supported | Kind is one of seven groups decided by extension. Contents are not inspected |
| Old files | Supported | Based on the last-modified time the browser reports; copied or extracted files may differ from the original |
| Empty folders | Partial | Known only when the folder is dropped or picked with “Choose folder” (in supporting browsers); not available otherwise |
| Duplicate candidates with the same name and size | Partial | Lists candidates only; contents are not compared. Confirm with Duplicate Files |
| Export to Excel, CSV and PNG | Supported | Excel has every report; CSV has the one you selected |
| Scanning a whole drive | Not supported | Only folders the browser lets you choose or drop are read; system folders and the like cannot be read |
| Space actually used on disk (cluster size) | Not supported | Totals are file sizes in bytes. With many small files the real disk usage is larger |
| Deleting or moving files and folders | Not supported | Analysis only; nothing is ever written to your files |
| Offline use | Supported | Works without a connection once loaded |
Limits & notes
- Up to 300,000 files can be loaded; anything beyond is not loaded and the screen says how many.
- Phone and tablet browsers may not support choosing or dropping folders. Pick several files or use a ZIP instead.
- The treemap shows at most 150 items per folder and the table 300 rows; smaller ones are merged into “N more items”. Report tables can show 10 to 500 rows.
- Files of size 0 have no area and are not drawn in the treemap (their count is shown).
- Sizes are the sum of file sizes, not the cluster-based space the OS reserves, and the OS’s handling of hard links and symbolic links is not visible here.
- Modified time is the last-modified time the browser reports; for files in a ZIP it is the time recorded in the ZIP.
Privacy & safety
Files are never uploaded: your browser reads references to the files and totals them on your device. File names, paths and contents are not sent, stored, or included in analytics or error reports (only usage figures such as file counts and size ranges are). The files you save are also created on your device.
FAQ
How do I find what uses the most space in a folder?
How is this different from WinDirStat or WizTree?
Why does it not match my disk usage?
Can it delete duplicate files?
Can it analyze a ZIP?
Are file or folder names sent anywhere?
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