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I need a free duplicate file finder/remover app, with ability to find duplicate files/folders by name and/or by size and to remove one of duplicates.

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closed as off topic by KronoS, terdon, Dennis, Everett, 8088 Mar 10 '13 at 20:06

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It's possible to do this using a BASH shell script: superuser.com/questions/386199/… –  Anderson Green Oct 13 '12 at 4:00
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15 Answers

up vote 9 down vote accepted

There was this Duplicate File Finder available for some time but now its only on secondary sites, like this Softpedia reference.

The Wareseeker site shows the correct reference http://dff.nazrashid.com/ which is no longer around. I would be careful fetching executables from such sites though.

It can do search for duplicates within multiple directory trees based on,

  • contents (i think it does a md5 match)
  • size
  • name
  • name and size
  • contents and name

And, it lets you filter your search by a minimum and maximum files size (speeds up things when you know the bounds).

A very thoughtful piece of software. Don't know if there is something as fast and featured for free around these days.


The comments refer to a similar Sourceforge tool called Doubles

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Actually it is available on SourceForge here: doubles.sourceforge.net –  Diago Jul 18 '09 at 21:05
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Can I suggest removing the Wareseaker link. I think we need to be careful when referring to Warez sites in general. –  Diago Jul 18 '09 at 21:10
    
I agree with you Diago. I tried locating the DupeFinder tool and could never find it. The doubles tool looks similar but its not the same thing. –  nik Jul 19 '09 at 4:15
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For what it's worth, I found the website (home page, at least) in the Wayback Machine: wayback.archive.org/web/20070115135708/http://dff.nazrashid.com with another download link: wayback.archive.org/web/20061207062803/http://dff.nazrashid.com/… –  seanf Dec 22 '13 at 13:41
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I have tried literally dozens of duplicate file finders (I still have the installers/ZIP files for about 20 of them sitting around). I used CloneMaster 2.19 for a time because it was the best one I could find, though even that wans’t perfect (I wanted one that could also detect duplicate MP3s by audio content, ignoring the tags). All of them had problems that frustrated me enough that I decided to write my own and laid out a list of the features I demand of a DFF.

And then I found AllDup. It is the first and only one that actually made me abandon a project (technically mine isn’t completely abandoned, it’s just no longer being worked on since I don’t need to write it anymore because AllDup does everything I want of it). Anyway, AllDup searches for duplicate files, but unlike the others, it uses a lot of the tricks and techniques that I was going to use in my own DFF. As such, it is very fast: it can for example scan >250,000 of sizes from 1B-5GB in ~30mins (I have done it on my system several times).

Another great (and for some reason rare) feature of AllDup is as I mentioned that it can scan for duplicate MP3s by their actually audio data while ignoring tags, so two MP3s that are the same but have differing tags (very common when downloading) will be detected as duplicates. (It could even detect when I ripped two identical songs from two different CDs—with different tags of course.) Of course it can detect dupes based on other factors besides byte-for-byte content, like filenames, dates, etc.

Other great features of AllDup include the ability to filter (include or exclude) based on filename and/or folder name and/or filesize. The results screen is also very versatile with options to select files based on date, path, name, this, that, the other… It also has variety in what to do with detected duplicates

Michael Thummerer is also very receptive. I have reported bugs and suggested features to him several times which he addressed extremely quickly (to the point that he told me to download and try out a beta with the updates in the very next emails the same day).

Oh and it’s free.

HTH

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The link doesn't work. –  Joseph Apr 8 '10 at 13:05
    
Thanks for the notice. I guess I must have typed the URL in manually and perseverated the GTLD. –  Synetech Apr 9 '10 at 12:42
    
No, what happened was Chrome’s auto-correct reversed the ‘e’ and ‘d’ (like it does when I try to type dr.) Grrr. (It’s fixed, for the record.) –  Synetech Mar 17 '11 at 5:42
    
I have also used many, and this is what I've settled on. The interface is a little clunky, but it has lots of useful options. –  endolith Jun 15 '11 at 13:48
    
Have you tried version 3? It is pretty sold. –  Synetech Jun 16 '11 at 1:52
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Duplicate Cleaner is very fast and it has extensive result set filtering possibilities.

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This looks nice. It's freeware, works in Windows 7, has a variety of filtering methods, and supports creation of NTFS hardlinks instead of deletion. –  endolith Jan 13 '10 at 15:52
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Can't handle Unicode filenames, though? –  endolith Jan 26 '10 at 20:10
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Does it handle duplicate folders? –  Anderson Green Sep 2 '12 at 16:51
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Actually, it does handle duplicate folders. This is the first program that I've found (so far) that can identify duplicate folders as well as duplicate files. –  Anderson Green Sep 2 '12 at 16:52
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Clonespy http://www.clonespy.com

I find this very helpful and more useful than doublekiller. A particularly nice feature is the "Pools" feature, where you can compare one group of directories with another group of directories while ignoring duplicates within the groups.

For example, my partner likes to keep duplicate image files while working with images. I want to see if I have any copies of those files in my directories.

Pool 1 - Partner Home Directory Pool 2 - My Home Directory.

The only duplicates found are if a file is present both in my directories and my partner's directories. The files only duplicated in my partner's directories are ignored.

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Can you use CloneSpy to find all of the duplicate files (or duplicate folders) in a specific directory? –  Anderson Green Sep 2 '12 at 11:05
    
@AndersonGreen Yes for duplicate files –  FelipeAls Sep 29 '12 at 19:10
    
This is the only dupe finder that I have come across that allows you to do cross compare of a single file (provided you put it in an adequate folder location) or a folder tree structure, against another folder tree structure (or a set of folders or tree structures). All the other tools I have tried throughout the years have failed at exactly this point! This is the only one that does this right. –  sammyg Apr 7 at 22:24
    
I have often found myself in a situation where I know I am looking at a file that has a duplicate copy somewhere else, but I can't remember where that other copy is stored. Sounds familiar? Or I know that the file is a copy of another file, and I even know the location of that other copy, but I have to compare it against it to see which one is the one I want to keep. I might even have two or three other copies or versions of it on that second location. This is the breaking point where the distinction between a diff tool and a dupe tool becomes foggy. –  sammyg Apr 7 at 22:31
    
The pool to pool comparison is simply a killer! This is a major advantage over other tools. As far as diff and dupe tools go I have yet to find one that forges both into one software. I think Beyond Compare comes close to that, but it's still a mile off. It definitely has the potential, and it's the best diff tools I've used. –  sammyg Apr 7 at 22:36
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I have the following batch file lying around for some time:

@ECHO OFF
REM TODO: Help when run with /? and switch for recursion
REM Furthermore check whether we might have enough files to hit the envvar length limit
REM and switch strategies accordingly (slower but finds all dupes then)
SETLOCAL ENABLEEXTENSIONS ENABLEDELAYEDEXPANSION
REM This method speeds up comparison but suffers from long file lists
REM as environment variables have a length limit
SET FILELIST=
FOR %1 %%i IN (*) DO (
    FOR %%j IN (!FILELIST!) DO (
    	IF %%~zi EQU %%~zj (
    		fc /b "%%~i" "%%~j">NUL && echo "%%~i" = "%%~j"
    	)
    )
    SET FILELIST=!FILELIST! "%%~i"
)
ENDLOCAL
GOTO :EOF

You can run it with /r as argument to run recursively through the directory tree.

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1  
Awesome geek solution! –  JBRWilkinson Jan 13 '10 at 17:40
    
Downvoter: It would help if you said why this wasn't helpful in your opinion. –  Јοеу Jan 27 '10 at 10:32
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Total Commander has a brilliant duplicate file finder utility. Unfortunately it is not free.

As nik mentioned there is the Duplicate File Finder which is open source and cross platform. It's available on SourceForge here

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DoubleKiller is an excellent free (they also have a pro version) duplicate file finder/remover. I've been using it for years and would thoroughly recommend it.

http://www.bigbangenterprises.de/en/doublekiller

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Winmerge http://winmerge.org/

Compare very similar directories, perhaps between your "Documents" folder and your impromptu "backup", "Copy of Documents" folder, you created several weeks ago "just in case".

You can figure out what files are still identical, which files are the newest (or oldest, if you have encountered a problem), and which files exist only in one place. Then you can "merge" the directories and delete the duplicates.

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Can you use WinMerge to obtain a list of duplicate files and folders within one specific directory? –  Anderson Green Sep 2 '12 at 11:06
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Duplocator. A cross-platform duplicate-finding python script.

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Link is broken. –  Nifle Feb 9 '10 at 23:54
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Advanced system care free comes with an Clone Files Finder with the program. I use it, and it works fine.

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I've always used an old program Find Duplicates, but now that Geocities has been killed off, I guess it doesn't exist anymore, so here's a copy of the file.

It displays the files in easy-to-see groups isolated by color. It warns you if you've marked all the copies of a file for deletion, can automark them, can selectively automark all files in a directory (I used this a lot), can delete directories that become empty after the deletions, etc. Be careful of links if you're using it in Wine. It will delete all copies of a file without knowing that they are links.

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I've switched to AllDup. –  endolith Jun 15 '11 at 13:48
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Fast Duplicate File Finder:

  • Completely Free
  • Can identify duplicates regardless of structure
  • Easy to use Windows UI
  • Can produce reports in XML form
  • Can Move the duplicates to the recycle bin or another root folder retaining the original folder structure
  • Fast binary comparison algorith as well as checking filename and size.

http://www.mindgems.com/products/Fast-Duplicate-File-Finder/Fast-Duplicate-File-Finder-About.htm

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I have found Yet Another Duplicate File Remover to be awesome. It is pretty new and very easy to use. I used it to compare over 50,000 files from a hard drive recovery project, so it can handle a large amount of files.

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The best solution I tested on windows was the already mentioned Alldup. Props to Synetech inc. for sharing it. Brilliant and very professional freeware tool.

In the post I provide tested bash solutions that will work under Cygwin, Linux and OS X (or anything that uses bash-like shell).

Looking for duplicate files using freeware and open source tools

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Can AllDup generate a list of duplicate folders instead of duplicate files? –  Anderson Green Sep 2 '12 at 2:50
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Another utility:

http://yurichev.com/ddff.html

* Comparison to other duplicate finding utilities:

+ Very fast
+ Comparing directories too.
+ Often, two directories contain, let's say, 4 equal files and 5th file is different.
  We handle it too and output these as "common files in directories"
+ Absence of unnecessary switches.

- Win32 only
- Command-line only
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