PXP is a validating XML parser for the programming language Objective Caml. It strictly implements the full XML-1.0 standard. The XML instance is represented as a tree of objects. It is also possible to access the DTD. PXP means "Polymorphic XML parser" and emphasizes its most useful property: that the API is polymorphic and can be configured such that different classes are used to store different types of elements. PXP contains a user's manual and several example, and has been designed with CGI programming in mind, however is not limited to this field.