A file synchronization and backup utility for Mac OS X.

DL #1:  Version 1.0 (PPC). English
DL #2:  Version 2.1.1 (PPC), English, French, German, Italian,
Japanese
DL #3:  Version 3.0.3 (PPC), English, French, German, Italian,
Japanese
DL #4:  Version 3.2.1 (PPC), Spanish
DL #5:  Version 3.2.3 (PPC), French, German, Japanese
DL #6:  Version 3.4.2 (PPC), English, Italian, Japanese
DL #7:  Version 3.4.3 (PPC), English, French, German
DL #8:  Version 3.5.0 (PPC), English, French, German
DL #9:  Version 3.6.1 (PPC), English, German, Japanese
DL #10:  Version 4.0 (PPC), English, French
DL #11:  Version 4.0.1 (PPC), English, Japanese
DL #12:  Version 4.0.2 (PPC), English
DL #13:  Version 4.1.1 (PPC), English, French, German, Japanese
DL #14:  Version 5.0 (PPC/Intel), English, French, German
DL #15:  Version 5.0.2 (PPC/Intel), English, French, German.
DL #16:  Version 5.0.4 (PPC/Intel), English
DL #17:  Version 6.0.7 (PPC/Intel), English, released in 2009
DL #18:  Version 6.3 (PPC/Intel), English, released in 2011
DL #19:  Version 6.6 (PPC/Intel), English, released in 2013
DL #20:  Instructions on how to fix registration problems if they
arise

Later versions will be progressively uploaded when they satisfy the 10
year rule.

Registration Information

For versions up to 3.5
Serial number: 1005-7199-5965-5555-SP

For versions 3.6.1 and 4.x
Serial number: 1208-5569-8462-2222-SP

For versions 5.x up to 6.6
Serial number: 1013-6956-1268-3573-SP

The serial numbers seem to only work with the English versions of
Synchronize Pro X. I do not have any for the non-English versions.

Synchronize! Pro X launches a secondary application called "SyncXReg"
that calls home and/or tracks the registration info. This process
continues to run after you quit the main application. Originally I
believe that there was difficulty in registering Synchronize! Pro X
after one failed attempt (for v. 6 at least). These days this problem
does not appear to exist (at least in my tests) regardless of whether
you are connected to the internet or not. However, if such a problem
arises, I found some instructions to resolve it (see the last download
item)

See also:  [Synchronize! and Synchronize! Pro][1]

Compatibility
Architecture: PPC x86 (Intel:Mac)

Versions 3.4.3 to 5.0.2 require Mac OS X 10.2.3 (Jaguar) at least
Versions 4.x and above are compatible with Mac OS X 10.4 (Tiger)
Version 5.0.4 requires Mac OS X 10.3 (Panther) at least
Version 6.0.7 requires Mac OS X 10.3 at least and is compatible with
Mac OS X 10.5 (Leopard)
Version 6.3 requires Mac OS X 10.4 at least and is compatible with Mac
OS X 10.7 (Lion)
Version 6.6 requires Mac OS X 10.4 at least and is compatible with Mac
OS X 10.9 (Mavericks)

  [1]: http://macintoshgarden.org/apps/synchronize-and-synchronize-pro