this is an IFs installable file system. and is free.
... some care needs to be taken here. The software is explicitly stated to be "freeware" - which is "no charge". I cannot find anything on any page on the site which states which licence this is released under.
However: it was originally developed as part of an academic thesis ... usually such things are proprietary to the institution the student is enrolled with. It is possible you need special permission to modify it. Another clue would be if the source is not available.
Most folk posting here wouldn't care much. But consider: someone may feel inspired to develop this approach for other non-windows filesystems. How free are they to do so?
I think we should be sure who owns the software before we start getting too enthusuastic about it being "free".