http://winmerge.org/
Aside from multi platform, BC has things like CSV compare and marking unimportant changes are fairly robust. I do personally prefer open source myself, but BC is certainly one of the few that I didn't mind paying for.
Aside from multi platform, BC has things like CSV compare and marking unimportant changes are fairly robust. I do personally prefer open source myself, but BC is certainly one of the few that I didn't mind paying for.