Disk Space Analyzer — Free Online Folder Size Scanner

A disk space analyzer scans your folders and files and shows you how much storage each one uses. It helps you quickly identify what is taking up space on your hard drive or SSD so you can decide what to delete, move, or archive to free up disk space.

Yes, completely free — no limits, no watermark, no ads. There is no account to create and no subscription. It is one of the free browser-based tools at jasperbernaers.com.

No. It runs entirely in your web browser, so there is nothing to download or install and no account to create. Just open the page, click Choose Folder and scan — ideal for locked-down or managed work machines where you cannot install desktop software.

No. This tool runs 100% in your browser using the File System Access API. Your files are never uploaded to any server. Only file names and sizes are read — file contents are never opened. You can verify this in your browser's network tab: zero outbound requests carry your data.

Yes. File contents are never read — only names and sizes. Nothing leaves your browser. The File System Access API requires you to explicitly grant permission for each folder you scan, so there is no risk of scanning something unintentionally.

It needs the File System Access API, supported in Google Chrome 86+, Microsoft Edge 86+, and other Chromium browsers such as Brave, Opera and Arc. If you open it in an unsupported browser, a compatibility notice appears at the top of the page.

Not yet. Firefox and Safari do not implement the folder-picking File System Access API that this tool relies on, so full-drive scanning is not available there. Use a Chromium-based browser such as Chrome, Edge, Brave or Opera for the best experience.

Yes. Because it runs in the browser, it works on any operating system with a Chromium browser — Windows, macOS, Linux and ChromeOS — with no platform-specific install.

It is designed for desktop. Most mobile browsers do not expose the folder-scanning File System Access API, so whole-folder analysis works best on a Windows, macOS, Linux or ChromeOS computer.

Yes. When the folder picker opens, navigate to your drive root (C:\ on Windows or / on macOS/Linux) and select it. The scan recursively walks all subfolders. Some system-protected folders may be skipped if the OS denies access — this is normal and expected.

Yes, as long as the drive is mounted and visible to your operating system. Just navigate to it in the folder picker. Scanning speed depends on the network or USB connection speed.

No — the analyzer is read-only and never modifies or deletes anything. It only reads names and sizes so it can show you where your space has gone. Once you have spotted the large folders, delete or move them yourself in File Explorer, Finder or your file manager.

Yes. Click Export CSV to download a full inventory of every folder and file with its size and file count. Open it in Excel, Google Sheets or a text editor, or share it with your team.

WinDirStat, TreeSize and WizTree are Windows desktop applications that require installation (WizTree is faster because it reads the NTFS master file table directly). This tool works right in your browser with nothing to install, on any OS — ideal for quick checks or machines where you cannot install software.

Scanning reads metadata (name and size) for every file in every subfolder recursively. A folder with hundreds of thousands of files or deeply nested subfolders takes longer. A live progress counter shows the tool working in real time.

Each bar shows how much of the parent folder's total size that item represents. A bar at 80% means the subfolder or file accounts for 80% of its parent's disk usage, so you can spot the biggest space consumers at a glance.

The tool reports the logical size of files (the number of bytes). Your OS may show size on disk, which differs because of filesystem cluster/allocation sizes and compression, and it may include files this tool skipped when the OS denied access. Small differences are normal.

Scan your drive, sort by size, and expand the largest folders. Common culprits are forgotten downloads, old backups and disk images, media caches, and developer folders like node_modules and .git. Confirm what each big folder is, then delete or move it in your file manager and rescan to see the space you reclaimed.