When comparing 7-Zip vs FreeFileSync, the Slant community recommends 7-Zip for most people. In the question“What are the best archiving tools for a data hoarder?” 7-Zip is ranked 1st while FreeFileSync is ranked 2nd. The most important reason people chose 7-Zip is:
7-Zip is licensed under GNU LGPL, and the *.7z format has support across all major operating systems. There should be no trouble opening the archives under any operating system, and no need to deal with messages bugging you to register or pay for the app. Source code can be found [here](http://www.7-zip.org/download.html).
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Free and open source
7-Zip is licensed under GNU LGPL, and the *.7z format has support across all major operating systems. There should be no trouble opening the archives under any operating system, and no need to deal with messages bugging you to register or pay for the app. Source code can be found here.
Pro High compression .7z format
Their own file format .7z that ships with 7-Zip is one of the best compression formats. 7z file format is usually more compact than Zip.
Pro Lightweight
Starts quickly.
Pro Explorer right-click menu integration
Makes it easy to open any archive file, or create new archives, without having to go open another program first.
Pro Very fast compression/decompression
7z is muli-threaded, allowing it to do very fast compression and decompression.
Pro Unobtrusive
No nag screen.
Pro It supports multiple protocols
It will work with MTP, FTP, SFTP, FTPS, and more.
Pro It can copy locked files
It supports Volume Shadow Copy Service, meaning that it can copy files even if they are in use or otherwise locked.
Pro Cross-platform
It runs on Windows, Linux and MacOS.
Pro Portable version available
Pro It is quite performant
Pro Google Drive support
FreeFileSync provides direct access to Google Drive, no additional software is needed.
Pro Completely free
Source code releases are provided under GPLv2.
Pro It supports realtime sync
It can be configured to constantly monitor two folders for changes and sync them instantly when a change is detected.
Pro It lets you program batch scripts
You can program your own jobs for execution as a script.
Pro It supports case sensitive synchronization
For Unix-like systems.
Pro It supports long file paths
It can copy files and folders with more than 260 characters in their paths.
Pro It supports versioning
Versioning is keeping multiple instances of the modifications of your files.
Pro It can sync both local disks and network shares
Cons
Con GUI looks dated
Could use a new fresh user interface.
Con XZ/LZMA2 format inadequate for long-term archiving
LZMA2 is unsafe and less efficient than the original LZMA. Use: 7Z LZMA Non-Solid, RAR 5 LZSS/PPMd Non-Solid, or ZIP Deflate. See here.
Con Does not support data recovery
It's not possible with 7-zip to add data recovery records to the archive which could repair minor integrity errors.
Con Does not preserve folder timestamps when copying
Con Memory hog
It runs a little slow on computers who don't have much RAM available.
Con Limited built in history
The program only remembers the latest set of folders you synced, so you have to save your syncs or create batch files.
Con A little intimidating for novices
If you never ran a file syncing software, this can be a little tricky to configure as your first one.
Con No backup encryption
Con It doesn't run on older Linux systems
It's dependencies don't allow it to run on older systems.