qBittorrent official forums

[removed]

Any should work perfectly well, external scripts are not necessarily exclusive to a particular client, only to the parameters that are passed to the script/program.
The parameters that qBT passes to external programs on completion are the path (%f) and the name (%n) so as long as the script handles those it will work.

Never really looked, as the kind of stuff I download doesn't come "rared" or "zipped" so I don't have need of any external programs.

downloaded folder as an option

%f is the path to the payload, (Linux & Windows)