WizTree is very fast and free for personal use. Bytopsy is the alternative when you want an open-source licence that also covers work, or a tool that cleans what it finds.
Side by side
| Feature | Bytopsy | WizTree |
|---|---|---|
| Price | Free, every feature | Free for personal use; commercial use needs a paid Supporter Code |
| Use at work or on clients' PCs | Yes, MIT licence | Needs a commercial licence |
| Source code | Open source | Not open source |
| How it scans | Walks the file system with standard Windows APIs | Reads the NTFS Master File Table directly |
| Treemap and largest files | Yes | Yes |
| Duplicates | Yes, plus similar photos | Yes |
| Cleanup with protection rules | Yes, undoable | No |
| WSL and Docker disks, drivers, app updates, startup | Yes | No |
| Terminal app | bytopsy-cli | Command-line export options |
| Platforms | Windows 64-bit | Windows (and WizTreeMac separately) |
WizTree details from diskanalyzer.com, October 2026. Something out of date? Tell us.
Where WizTree wins
Speed. Reading the Master File Table straight from an NTFS drive means a scan takes seconds where a normal walk of the folders takes longer, especially on big drives with millions of files. Bytopsy does not read the MFT, so it needs a little more time, in return for working the same way on every kind of drive and counting hard links when you ask it to. If scan time is the only thing that matters to you, WizTree is hard to beat.
Where Bytopsy wins
- The licence. WizTree's free licence is for personal use. If you repair PCs, work in IT or use it on a company machine, you need a commercial licence. Bytopsy is MIT: free for everything, with no code to buy.
- You can read it. The whole program is public, so you can see what it does and what it never does, such as sending anything anywhere.
- It cleans, safely. Temporary files, caches, developer junk and AI model downloads are measured and checked against protection rules before anything is removed, and deletes go to the Recycle Bin by default.
- It looks after more than the disk. WSL and Docker disks, Windows' own reserved space, drivers through Windows Update, apps through winget, startup entries and drive health.
Try it
Bytopsy is a portable zip, so you can run it next to WizTree and compare the two on your own drive. If you are choosing between several analyzers, see Bytopsy vs WinDirStat and the TreeSize Free alternative.