These guys are fast!
Just hours since Kickass Torrents was taken offline, a mirror has been already created by isoHunt, which can be accessed kickasstorrents.website.
The site looks like the original KAT site, and it is upon keen observation that one can notice that is a mirror.
However, there is a warning; not everything is available and there is no forum, community, or support available.
It should be noted that the same isoHunt team was behind the resurrection of The Pirate Bay when it was taken offline.
