Bytopsy is a free, open-source disk analyzer and PC cleaner for Windows. Find what fills your drive, clean it without breaking anything, and keep drivers, apps and disks healthy.
The treemap shows the whole drive at once, coloured by kind, so a 38 GB video or a forgotten virtual disk jumps out. The search box speaks size, age and type. Try it on this sample drive.
Point at a block to see what it is. Every block is a file or folder, drawn to scale.
Real screenshots of Bytopsy. Choose a view, or let it play.
What other cleaners sell in their paid tier, free and without the risk: nothing from third-party driver databases, and every install through Windows' or the app's own mechanism.
Bytopsy asks Windows Update which driver updates exist for this PC, shows them next to the installed version and date, and installs the ones you pick through Windows Update itself, with a restore point first. Graphics go to the vendor's own app.
An Updates filter in Apps. Update one app or all of them, each through its own installer. If winget is missing, Bytopsy repairs it or links to it.
A Windows notification when a drive drops below the limit you choose. No program stays running.
Off by default. The update manifest is signed, the download is checked against its SHA-256, and installs from winget, Scoop or Chocolatey are left to their package manager.
Their .vhdx files grow but never shrink. See the size on the drive next to what Linux really uses, then compact them the way Microsoft documents it.
Resized, re-saved or rotated copies, found by perceptual hash. One per group is suggested to keep; nothing is selected for you.
Steam, Epic, GOG, EA, Ubisoft, Battle.net and Xbox in one list, with when each was last played. Uninstalls go through the launcher.
Run keys, Startup folders, logon tasks and services, with an honest impact. Turning one off never deletes it, and Task Manager agrees.
Runs the app's own uninstaller, waits for it, then shows the folders it left behind. Folders other apps use are never offered.
Daily, weekly or at logon, through a task of your own. No background process, no administrator rights, never on battery.
Every scan is kept. Scan the same drive next month and see exactly which folders grew or shrank.
Right-click any folder or drive and pick Analyze with Bytopsy. Per user, no admin rights, removed by the same switch.
The window describes itself to Narrator, NVDA and JAWS: every view, list row, button and dialog.
Every delete and every cleanup item is checked against protection rules first: the item, its folder and everything inside it.
Never deleted. Drive roots, Windows, Program Files roots, your profile, registry hives, pagefile and hiberfil.
An extra warning that says what would be lost. AI assistant data, SSH keys, wallets, browser profiles, mail, game saves, Git repositories.
A heads-up in the delete dialog. Local AI models, .env and .pem files, virtual disks, Downloads.
Every delete is written to the journal. Anything still in the Recycle Bin comes back with one click.
The whole registry is a few hundred megabytes, so “cleaning” it frees nothing you could measure, and Windows doesn't get faster. What it does do is break installers, repairs and file associations. Bytopsy only touches the registry when you ask, and every change can be undone.
How Bytopsy stacks up against the cleaners most PCs come with.
| Feature | BytopsyFree | CCleanerFree + Pro | IObit ASCFree + Pro |
|---|---|---|---|
| Every feature free | Yes | Pro is a yearly licence | Pro is a yearly licence |
| Open source | Yes | No | No |
| Registry cleaner | None, on purpose | Included | Included |
| Driver updates | From Windows Update | Paid tier | Separate product |
| Telemetry | None at all | See their policy | See their policy |
| Deleted files | Recycle Bin + journal | Varies by tool | Varies by tool |
From each vendor's public product pages, October 2026. IObit ASC is Advanced SystemCare; its driver updates come from Driver Booster, a separate product. CCleaner and IObit are trademarks of their owners. Something out of date? Tell us.
Two self-contained .exe files, native C++ with no runtime and no installer. Drop a bytopsy.portable file next to them and everything they write stays on the stick, ready for the next client's PC.
PS C:\> bytopsy-cli --clean all-safe
Dry run: nothing is deleted. Add --yes to clean.
349.5 MiB 41 items Recycle Bin [recycle]
3.0 GiB 180 files Temporary files [temp] (12 protected items left out)
skipped Windows temporary files [wintemp]: needs administrator rights
1.2 GiB 11,568 files Browser caches [browser]
430.0 KiB 10 files Chat app caches [chat]
22.2 MiB 30 files Thumbnail cache [thumbs]
4.9 MiB 21 files Graphics shader caches [shader]
Would free 4.5 GiB. Run again with --yes to clean.
No telemetry, no tracking, no account. Everything Bytopsy writes lives in one folder you can delete. The only network access is the update check, and it's off until you turn it on.
Yes, every feature, for everyone. It's MIT licensed: use it at home, at work and on your clients' PCs, change it and share it. There's no Pro tier, no trial and no ads.
Because it frees nothing you could measure and breaks things you can. The whole registry is a few hundred megabytes, Windows only reads the keys it needs, and a key that looks orphaned is often read later by an installer, a repair or a file association. Microsoft doesn't support registry cleaners for this reason.
No. The Bytopsy program has no telemetry and no tracking, and what it learns about your disk stays on your PC. The only network access is the update check, and it's off unless you turn it on: then it asks bytopsy.com, or GitHub as a fallback, for the latest version. This website counts visits with Google Analytics only if you accept, and the program never does.
It's built not to. Drive roots, Windows, your profile and registry hives are Blocked. SSH keys, wallets, game saves, mail, AI assistant data and Git repositories are Important and get an extra warning. Deletes go to the Recycle Bin by default, and the journal can restore them.
From Windows Update, asked through Windows' own API: Microsoft-signed drivers matched to your hardware. Graphics drivers go through the vendor's own app (NVIDIA app, AMD Software: Adrenalin, Intel Driver & Support Assistant). Never a third-party driver database.
Until code signing through the SignPath Foundation is in place, releases aren't signed, so Windows doesn't know the publisher yet. Every release has a SHA-256 file beside it to check your download against, and the whole build runs in public on GitHub Actions. See the code signing policy on the download page.
No. Scanning, cleanup and almost every view work as a normal user. Windows asks for permission only for the few actions that need it, such as compacting a WSL disk or cleaning Windows Update downloads.
Like WinDirStat it is free and open source, and like WizTree and TreeSize it draws a treemap of every file. Bytopsy is MIT licensed with no personal-use limit, keeps scan history, finds duplicates and similar photos, and goes on to clean what it finds, with protection rules and an undo journal. WizTree is quicker on a big NTFS drive because it reads the file table directly.
Scan the drive with Bytopsy, as administrator so Windows' protected folders are counted, then follow the biggest rectangle in the treemap down through the folder list until you reach something you recognise. The guide on this site walks through the hidden space Windows keeps for itself.
How to find what fills a drive, free it safely, and choose between the tools. No upsell in any of them.
Find what is filling your drive, then free the space without breaking Windows: built-in tools first, what is safe to delete, and what to leave alone.
How to see exactly which folders and files fill your C: drive on Windows, including the hidden ones: hiberfil.sys, pagefile.sys, WinSxS, restore points and virtual disks.
Why ext4.vhdx and docker_data.vhdx grow but never shrink, how to see how much is really used, and how to compact the disk the way Microsoft documents it.
What a registry cleaner actually removes, why it frees nothing you can measure, why Microsoft doesn't support them, and what to do instead to speed up a slow PC.
Bytopsy is a free and open-source PC cleaner for Windows: every feature free, no Pro tier, no ads, no registry cleaner, and every delete can be undone.
WinDirStat is free and open source, and so is Bytopsy. How the two disk space analyzers differ: cleanup, protection rules, drivers, WSL, history, and the terminal app.
WizTree is free for personal use only. Bytopsy is MIT licensed: free at home, at work and on clients' PCs, and it can clean what it finds.
TreeSize Free is for private, non-commercial use on desktops. Bytopsy is MIT licensed and adds duplicates, old files, history and safe cleanup at no cost.
Download the zip, check it against its SHA-256 and unpack it anywhere. No installer, no account, no email.