The Autopsy and Sleuth Kit are both open source and together they can analyze Windows and UNIX disks and file systems (NTFS, FAT, UFS1/2, Ext2/3, etc.). Plugin architecture allows you to find add-on modules or develop custom in Java or Python.
Autopsy is a free digital forensics platform and graphical user interface (GUI) to The Sleuth Kit and other open source digital forensics tools, that allows you to efficiently analyze hard drives and smart phones or even recover photos from your camera’s memory card, etc.