TrID - Allows to detect file type by recognition of binary signatures.
TrIDNet - TRIDNet is the GUI version of TrID, probably more practical to use than the CLI version, especially...
file - file is a standard Unix program for recognizing the type of data contained in a computer file using...
JHOVE - JHOVE is a file format identification, validation and characterisation tool. It is implemented as a Java application and is usable on any Unix, Windows, or OS X platform with appropriate Java installation.
ImageJ - and Other Health Care
DROID - Perform automated batch identification of file formats.