1. Method for A/B testing or multivariate testing of a website on a computer being connected to a web content management system, comprising: storing, at the web content management system, website content data in the form of stored content objects and one or more website variants, wherein each of the one or more stored website variants represents data that defines a structure of one or more webpages of the website on the basis of said stored content objects, creating, at the web content management system, markup language representation data of one or more webpages on the basis of at least one of the stored website variants and the stored content objects indicated by said at least one of the stored website variants, receiving, at the web content management system from a requesting computer, a webpage data request directed to at least one webpage of the website for which at least two website variants including a first website variant and a second website variant are defined, and selecting one website variant of the at least two website variants of the website; wherein: if the first website variant is selected, the method further comprises: creating, at the web content management system, first markup language representation data of the at least one webpage on the basis of the first website variant and the content objects indicated by the first website variant, and providing the requesting computer with the first markup language representation data of the webpage; and if the second website variant is selected, the method further comprises: creating, at the web content management system, first markup language representation data of the at least one webpage on the basis of the first website variant and the content objects indicated by the first website variant, creating, at the web content management system, second markup language representation data of the at least one webpage on the basis of the second website variant of the website and the content objects indicated by the second website variant, determining, at the web content management system, differences between the created first and second markup language representations of the at least one webpage, creating, at the web content management system, webpage difference data on the basis of the determined differences, the created webpage difference data indicating the differences between the first and second markup language representation data of the at least one webpage, providing the requesting computer with the first markup language representation data of the at least one webpage, and providing the requesting computer with the created webpage difference data for post-processing of the first markup language representation at the requesting computer on the basis of the webpage difference data.