The package provides a parser \poldef of algebraic polynomial expressions. As it is based on xintexpr, the coefficients are allowed to be arbitrary rational numbers. Once defined, a polynomial is usable by its name either as a numerical function in \xintexpr/\xinteval, or for additional polynomial definitions, or as argument to the package macros. The localization of real roots to arbitrary precision as well as the determination of all rational roots is implemented via such macros. Since release 0.8, polexpr extends the xintexpr syntax to recognize polynomials as a new variable type (and not only as functions). Functionality which previously was implemented via macros such as the computation of a greatest common divisor is now available directly in \xintexpr, \xinteval or \poldef via infix or functional syntax.