Visualizing the structure of binary files
For PDF files, see https://stackoverflow.com/questions/3549541/best-tool-for-inspecting-pdf-files
One of them is iText RUPS.
See also http://kaitai.io/ — not sure whether it includes a visualizer.
I’m trying to write something similar for DVI files (because no one else will).
(Thanks for reading! If you have any feedback or see anything to correct, contact me or edit this page on GitHub.)