What Does a Registry Cleaner Do?

Does a registry cleaner actually clean something in the Windows Registry?

Closeup view of the question mark key on a computer keyboard
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A registry cleaner is a software program that scans the Windows Registry for entries that once had a purpose but, for at least one of several reasons, no longer needs to be there.

Once found, the registry cleaner presents those entries to you on the screen, will sometimes rank them by importance, and then suggests that you allow the program to automatically remove some or all of them from the registry.

While that might sound pretty straightforward, which it is, what makes one registry cleaner different from another is how well a program does this task, as well as what entries, called registry keys, a program has predetermined is bad or unnecessary.

Please know that just because registry cleaners exist, and they do something in the registry, doesn't mean that they're necessary tools that computer users everywhere should be using.

What Does a Registry Cleaner Do?

The Windows Registry doesn't get "dirty" and thus need cleaning. Registry cleaners do, however, do a great job at fixing certain kinds of problems.

Here are some examples from the popular CCleaner tool:

  • Missing shared DLLs
  • Unused file extensions
  • Type libraries
  • Applications
  • Fonts
  • Application paths
  • Help files
  • Installer
  • Obsolete software
  • Run at startup
  • Start menu ordering
  • Sound events
  • Windows services

CCleaner lets you pick which of those categories that you want the program to scan. For example, if you scan for registry issues related to obsolete software, the program will look for software that has been removed from your computer but that still has entries in the registry.

Or maybe the registry cleaner you're using will find redundant or empty entries in the Windows Registry, in which case deleting those items will provide the benefit of better organization.

Menu ordering is another common area of Windows that a registry cleaner will scan. What this does is deletes any customizations you've made to certain menus, effectively resetting them back to the way they were before you made changes.

Beyond choosing what to look for, a registry cleaner usually also gives you an opportunity to pick what should be deleted from the results, plus whether you want to back up the registry first. After a scan, the registry cleaner might provide a summary of what was cleaned and may even give you an "estimate" of the free space or performance improvements you can expect from the cleanup.

More Information on Registry Cleaners

Some registry cleaners are really multipurpose tools that can do a lot more than just clean up registry items. They might also defrag the hard drive, delete temporary files, remove browser caches, and more.

Because there are so many registry cleaner programs out there, and many of them serve as more than just a Windows Registry related tool, be extra careful to download registry cleaners from trusted sources only. It's common for malware to be transmitted in these programs.

Good registry cleaners can be had for free. You do not need to buy one. Registry cleaners you pay for do not necessarily work any better than the free ones. See our list of completely free registry cleaning tools to avoid ones that charge you.

If this is the first place you're learning about registry cleaners and what they are, we highly recommend that you read through the rest of the FAQ.

If you're in a hurry, at very least read through these pieces:

There's a lot of misinformation out there about the value and necessity of registry cleaning that those pieces should help clear up for you.