The package is a toolbox of programming facilities geared
primarily towards LaTeX class and package authors. It provides
LaTeX frontends to some of the new primitives provided by e-TeX
as well as some generic tools which are not strictly related to
e-TeX but match the profile of this package. Note that the
initial versions of this package were released under the name
elatex. The package provides functions that seem to offer
alternative ways of implementing some LaTeX kernel commands;
nevertheless, the package will not modify any part of the LaTeX
kernel.

Homepage:
https://ctan.org/pkg/etoolbox
