TrID - Allows to detect file type by recognition of binary signatures.
draw.io - Online diagramming application
file - file is a standard Unix program for recognizing the type of data contained in a computer file using...
LucidChart - LucidChart is the missing link in online productivity suites. LucidChart allows users to create, collaborate on, and publish attractive flowcharts and other diagrams from a web browser.
TrIDNet - TRIDNet is the GUI version of TrID, probably more practical to use than the CLI version, especially...
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.