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RegMerge is down for maintenance. If you want this utility to return, send us a note to express your interest - or donate. Thank you!

The SAFER way to import .REG files! With RegMerge you load up one or more .REG files and compare them to your current registry, allowing you to selectively import parts, or just see the changes. This is useful for REG file fixes you find on the internet, or comparing your registry with another PC or your own PC in an earlier state.

  • Import REG files safely and selectively
    Instead of wondering what a REG file will change, or if it is even different than your current registry, you can now see what it will change and selectively apply portions of it, or all of it
  • Compare
    By comparing your registry to that of another system, or an earlier state of your own system, you can determine likely causes of problems.
  • Multi-import
    Load up multiple REG files at once if you want or need.

What is a REG file?

Once you determine you've got a messed up shell file association, or other potential registry problem, you may search the web. You'll often find files with the extension .REG. These are RegEdit import/export files. With the Windows RegEdit utility you can right-click on any key and export a .REG file. Then, you can take this .REG file and import it to another system by double clicking it. This lets people provide you with .REG files to repair your registry. However, when you double-click one, you get the simple option of importing it - nothing more. It overwrites any content already there. So, you had better check to see what you are importing and compare it to what is currently there. In this way, you can make sure the REG file is actually solving the problem and not causing additional harm.

Obviously, What is needed is a utility to take a REG file, compare it to your current registry hives, and show you the changes it would make -- then allow you to selectively apply those changes. That is what our freeware utility RegMerge does. It shows you the changes between the REG file you are importing and your current registry HIVE(s). It can also let you COMPARE and CONTRAST the differences between a fresh install of an OS and your install.

Screenshot (may have changed since this):
RegMerge Screenshot

    Safety features: (some not fully tested or completed at this stage)
  • UNDO
    Creates an UNDO REG file for every change set that is applied
  • LOG
    Log changes and errors

Again, to CREATE .REG files for backups or comparison, use Window's RegEdit utility (RegEdit.exe). Simply select a key, right-click it and select 'Export'. This will create a .REG file.

The future

There are numerous planned enhancements to this utility that will occur incrementally. At this time, it is best not to submit any feature suggestions. We have a long list that probably already includes everything you've considered. There are some obvious improvements that need to be made. Again, this is an early alpha prototype.

The Community

Here is where YOU come in. We can not possibly collect repair sets for all Windows OSes and applications in the world. In fact, the more specific a repair set, the more likely it is the be useful. We are therefore going to leave it up to the community to help contribute repair sets.

We hope the community will help build an extensive REG repair set collection, so that users can use it for select repairs, return to defaults, and other operations. More on this soon. Remember, this is FREEWARE and will be an OPEN, COMMUNITY project.


Q: What do the different hives mean, and what settings do they affect?

This is important to know so that you can determine what parts of the system they affect. By knowing this, you can know which hive(s) you may need to take snapshots of, to later compare changes that have been done. A quick overview would be:

Registry Damage Repair

We all know that the #1 issue that mandates OS reinstalls is registry corruption. I didn't say registry 'fat', I said corruption. Often, registry cleaners themselves are the cause of this corruption. Regardless, over the normal lifespan of a Windos install, the registry gets changed and manipulated. Wouldn't it be nice to know what all has changed? Maybe go back to defaults? Apply fixes selectively and safely?

    Registry issues come from:
  • Registry Cleaner use
  • Application install/uninstalls (shell file association damage usually)
  • System tweaking utilities change system registry values
  • Manual user registry edits
  • Manual user changes of 'open with' (shell file associations)
  • Malware
  • Disk corruption

Call this the opposite of a registry clean. The idea here is NOT TO REMOVE keys, it is to ADD and REPLACE keys and values. That's right - make your registry right again, not just pointlessly trim it down.

Facts about Registry Cleaners

Poorly written registry cleaners cause damage

This is a fact. Many of the Application Compatibility Updates you get from Microsoft are to fix damage to critical OS registry keys. There is simply no way for a registry cleaner to know for certain whether a key is still in use or not. It therefore has to make an educated guess. A well written cleaner will avoid mistakes, but a poorly written one will delete many important keys.

Registry cleaners are often far too aggressive

Since registry cleaners often try to beat their competition by increasing the count of keys deleted, many tend is to be overly aggressive when deleting keys.

Removal of registry keys does NOT boost performance

Unreleased third-party benchmarks using RegBench have shown that popular registry cleaners ran on a typical real-world PC do not boost registry performance one bit. Only rebuilding the hives from scratch (described elsewhere on this page) boosts performance. This is in line with theoretical predictions. Your registry has hundreds of thousands of keys. Your registry is loaded into virtual memory in an optimal data structure allowing for very quick traversal (searches). Deleting a few hundred (or even thousand) keys isn't going to make it perform faster. Some people suggest that utilities that correct keys with errorneous values may speed the system, if those errorneous values were slowing it down. However, we consider these the 'registry repair' genre instead of 'registy cleaner'.

The best theoretical way to boost registry performance is ...

The best theoretical way to boost registry performance is NOT by deleting keys, but instead by rebuilding the registry hives from scratch and/or defragmenting the backing hive files (in the case of HDDs). HOWEVER, defragmentation of the backing hives on the HDD is now redundant in NT 6 (Vista) and above, as the OS does it for you. There are many freeware utilities to hive rebuilding (e.g. NTRegOpt), but be careful with them as some are incompatible with Vista+ and may result in an unbootable system. Before use, make a backup of your registry hive files and be sure you know how to restore them in the event they are corrupted. It is also important to remember that any gains to registry performance are likely to very marginal, and probably nothing you do to the registry will substantially increase overall system performance.

For more information about Registry Cleaners in general, see the Wikipedia article on the subject.


RegMerge is *not* a registry cleaner or automated registry repair utility. It is an advanced utility for those who know what a .REG file is.

Manual registry repair via safer .REG file imports! No more blind .REG importing, see what changes the .REG file will make and/or selectively apply its changes.


Current version:
v0.0.1.1 alpha - 01/17/2016

Other freeware



    v0.0.1.0 ALPHA
  • Added single-click Bitsum Updater
  • Added installer
  • Added shell integration
  • Added REG file command line support

WARNING: This is an early alpha that has not been fully tested at all. Its purpose is further testing to discover bugs and continue the refinement process. Do not use unless you are prepared to have registry damage (assuming the worst). Backup your registry hives/keys using regedit's 'Export' function and create a system restore point before using this software. To use this utility, YOU must agree to accept all responsibility and liability for any damages, tangible or intangible, resulting from the use or misuse of this utility. This utility is for PC technicians and advanced power users. You have been warned!

It has NOT been tested in Windows 2000 or Windows XP. I have only tested it in Windows 7 x64 at this time. It is literally fresh off the assembly line. To avoid any issues with WOW64 Registry Redirection, I've decided to issue a 32-bit and 64-bit build.

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