There is a free edition of FileSieve that is available for use; it is restricted in specific ways.
Please see the Edition Comparison page for a comparison between the different versions.
FileSieve is currently only available as an installer; a portable version may be released at a later date.
To use FileSieve 4, you will need to meet the following minimum requirements.
A Windows operating system that is Windows 10 1607 or higher is required. This is an indirect FileSieve requirement; version 4.8 of the Microsoft .NET framework requires at least this version of the OS.
If you're using pre-Windows 10, you can instead use the previous FileSieve 3 release series.