InstallerClean

InstallerClean finds and removes unneeded files from C:\Windows\Installer, the hidden folder on every Windows PC that quietly accumulates installer copies and patch files. Windows never cleans this folder up. Disk Cleanup doesn't touch it. DISM is for a different folder entirely. Over years it grows to tens of gigabytes, and on machines with heavy MSI-using software (Adobe Acrobat is a frequent culprit) it can pass 100 GB.

The app identifies three kinds of removable files: orphaned .msi installers and .msp patches left behind after you uninstall software, superseded patches that a newer patch has replaced, and obsoleted patches the publisher has withdrawn. It calls the Windows Installer API directly to determine which files are still registered, rather than guessing from filenames or dates, and reads the same records from the registry as a second independent source, which can only ever add files to the "still needed" side. Optional detail windows show every file, its size and why it's removable.

Safety is the default. Delete sends files to the Recycle Bin; if the Recycle Bin isn't available for that drive, it offers to move them or asks for explicit consent instead of silently deleting for good. Move copies files to a folder you choose, so you can keep them aside before committing. Nothing is touched until you confirm, and both actions can be cancelled while running. Pending-reboot detection blocks a clean if Windows updates in flight could make it unsafe.

Anonymous, opt-in reports from users so far show 56% of machines had unneeded files, with a median 18.8 GB freed on those, and one machine reclaiming 327 GB.

InstallerClean is a modern open source alternative to PatchCleaner, which was last updated in March 2016. Where PatchCleaner hides every Adobe file behind a blanket filter, InstallerClean reads the patch records and labels superseded Adobe patches as exactly that. It ships as a setup, a portable exe and a standalone command-line tool for scheduled clean-ups and mass deployment, with a screen-reader-friendly interface available in 16 languages.

Written in C# on .NET 10 with a WPF interface. Apache 2.0 licensed, no telemetry, no account, no ads, and the only network activity is an optional check of GitHub for a newer version, which you can turn off.