The package emulates large parts of TeX’s behaviour when it chews on tokens, expanding and performing typesetting commands. Using unravel will let you go one step at a time through some complicated LaTeX code that you are trying to debug. It understands a whole breadth of TeX’s features, from deeply nested expansion to box assignments, to characters, and the proper insertion of \everypar.

The unravel package requires up-to-date l3kernel and l3experimental bundles, as well as the new package gtl.

The author is Bruno Le Floch. The package is Copyright © 2013 Bruno Le Floch.