Texapi provides utility macros to write format-independent (and
-aware) packages. It is similar in spirit to the etoolbox,
except that it isn't tied to LaTeX. Tools include: engine and
format detection, expansion control, command definition and
manipulation, various testing macros, string operations, and
highly customizable while and for loops. The package requires e-
TeX (and, should you want to compile its documentation, the
pitex package is also needed).