AnyTool
Your files never leave your device. All processing happens locally in your browser.

How do I see what is taking up space in a folder online?

Open AnyTool's File Size Analyzer and scan a folder — it reads only file sizes and names in your browser (never the contents, never uploaded) and shows what's using space as an interactive treemap and sunburst, plus a drill-down folder list, a breakdown by file type and extension, and your largest files. It works in Chrome and Edge via the File System Access API, and in Firefox and Safari via folder upload — all 100% local.

  • Scans a whole folder in the browser — no upload
  • Treemap + sunburst + drill-down + largest files
  • Breakdown by file type and extension
  • Works in every browser (and on mobile via file select)

What is

Disk usage analyzer

A disk usage (or disk space) analyzer scans a folder or drive and shows which folders and files take up the most space, usually as a treemap or sunburst chart so large items are easy to spot. Classic desktop examples are WinDirStat, WizTree, TreeSize and DaisyDisk; a browser-based one does the same without installing anything.

File Tools

Related terms

treemapsunburstfolder sizedisk spaceWinDirStat alternative

How to Analyze Folder Size

Visualize what is using disk space, entirely in your browser.

20 secWeb browser
  1. 1

    Scan a folder

    Click “Scan folder” (or drop a folder). Files are read locally — nothing is uploaded.

  2. 2

    Explore

    View the treemap or sunburst, click tiles to drill into folders, and check the largest-files list.

  3. 3

    Break it down

    See usage by type and extension, then export the full file list as CSV.

Result: An interactive picture of what is using your disk space

Frequently Asked Questions

With AnyTool, yes — it reads only file sizes and names in your browser and never uploads anything.

The File Size Analyzer reads file metadata (name, size, path) locally; file contents are never read and nothing is sent to a server, so even a private folder stays on your device.

Yes — in Chrome and Edge it uses the File System Access API to read folder metadata locally; Firefox and Safari use folder upload, still local.

Modern browsers let a page read a chosen folder's file list without transmitting it. AnyTool uses the File System Access API where available and falls back to an in-browser folder selection elsewhere — in every case the data stays in your browser.

Yes — AnyTool's File Size Analyzer is a free, no-install, cross-platform treemap/sunburst analyzer that runs entirely in your browser.

Unlike WinDirStat, WizTree, TreeSize or DaisyDisk, it needs no installation and works on Windows, macOS, Linux, and mobile, with both treemap and sunburst views and a largest-files list.

Detailed Explanation

Methodology

How the File Size Analyzer Works

AnyTool scans a folder entirely in the browser. In Chromium browsers it uses the File System Access API (showDirectoryPicker) to recurse the directory; in Firefox and Safari it falls back to an <input type="file" webkitdirectory> selection, and it also accepts a folder drag-drop via webkitGetAsEntry. Only file metadata — name, size and relative path — is ever read; file contents are never opened, which makes the scan fast and fully private. The flat record list is built into a folder hierarchy and aggregated bottom-up in a Web Worker, then visualized as a hand-rolled squarified treemap and a partition sunburst, with folder drill-down, a by-type and by-extension breakdown, and a largest-files list. Nothing is uploaded.

  • Runs client-side — file contents are never read or uploaded
  • Folder scan via File System Access API (Chrome/Edge) + webkitdirectory fallback (Firefox/Safari) + folder drag-drop
  • Squarified treemap + sunburst, both computed in-app (no chart library, no CDN)
  • Folder drill-down with breadcrumb, by-type and by-extension breakdown
  • Largest-files list and CSV export of the full file list
  • Aggregation runs in a Web Worker so large scans stay smooth
Privacy & Security

Privacy vs Desktop and Upload Tools

Desktop analyzers like WinDirStat, WizTree, TreeSize and DaisyDisk require installation and are tied to one operating system, while the only browser-based folder scanner alternatives are Chromium-only and offer just a folder tree. AnyTool runs in every browser including mobile, reads only metadata locally, and never transmits your file list — so it is both more private and more portable than the alternatives, at no cost and with no signup.

Disk-usage analysis: AnyTool vs desktop tools vs other web tools
CapabilityAnyToolDesktop toolsOther web tools
Install requiredNo — runs in browserYesNo
PlatformsWindows / macOS / Linux / mobileUsually one OSOften Chrome/Edge only
VisualizationsTreemap + sunburst + listsTreemap or sunburstFolder tree only
Data handlingMetadata read locally, no uploadLocalLocal (metadata)
PriceFree, no signupFree to ~$53Free

Desktop tools (e.g. WizTree) scan NTFS faster via the MFT; AnyTool wins on no-install, cross-platform, privacy and visualization breadth.