Easy Way to Compare Folder Contents?

I’m not looking for a duplicate file finder, but just the opposite. What I’d like to do is find what files are Not in one directory but is in the other, and vice-versa.

But it’s not just one folder, it’s 851 folders with over 63K files.

Long story short, I recently had issues copying the above files/folders from my computer to an external drive. Fortunately, I had the foresight to note down most of the error messages and later copied over thousands of files to the external drive that Windows didn’t.

But I’m down to a handful of files that I don’t know what or where they are in the computer to copy them over for a backup.

Any utilities out there that can do this? Any ideas or suggestions?
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It sounds like you want two copies of all files and right now you only have one copy in many cases, and that copy may be on the main drive or the backup drive. If so, then you are needing to synchronize both drives starting from a parent directory, such as "data" below.


I use robocopy and execute the following two commands in a cmd file to synchronize folders between my main drive and my external drive. So if either drive has a copy of a file and the other drive does not, it makes sure they both have the file after execution. Or if each has a certain file but one drive has a more recently updated version of that file, then the older file gets overwritten with the newer file. Robocopy has a lot of uses, this is just one. I use a cmd file but you can also execute it from the command prompt. If you prefer to use a GUI interface, EazyCopy is supposed to be similar to robocopy but with a gui. I have not used it.



start /w robocopy \\C\data\ \\D\data\ /s /xo
start /w robocopy \\D\data\ \\C\data\ /s /xo

Thanks folks for the tips