iNTFS is described as 'Today we’re going to introduce iNTFS, which we like to define as the killer app for having NTFS support on Mac OS' and is an app. There are four alternatives to iNTFS for Mac. The best alternative is Paragon NTFS for Mac OS X. It's not free, so if you're looking for a free alternative, you could try macFUSE or Mounty for NTFS.
The fastest way to read and write Windows disks from Mac OS X, which doesn't support writing to NTFS volumes out-of-the box. It builds and extends upon the proven stability of the open source NTFS-3G to deliver a full featured, commercial grade NTFS driver for your Mac.