The purpose of this thesis was to research which factors make Content Management System search engine friendly and to compare the search en-gine friendliness of CMS. The assignment of this thesis came from Frugal Ltd. Five CMS platforms were chosen to comparison. The chosen plat-forms were Joomla, Drupal, Wordpress, ModX and Concrete5. Used theo-ry was mainly based on the official guide of search engine friendliness by Google and The Art of SEO book by E. Enge, S. Spencer, R. Fishkin and J.C. Stricchiola who are recognized to be important authors in the business.

The first phase in this research was to list the known factors which affect search engine friendliness. During the second phase a query was sent to Finnish search engine optimization authors to find out which of the studied factors were the most important. In the third and last phase there was a comparison of search engine friendliness in Content Management Systems.

As the result of the query ten-most-affecting-factors in search engine friendliness were found. These factors were the page title, search engine friendly URL-paths, the categorization structure, the H1-element, 301-redirections, possibility to edit anchor-texts, navigation based on links, meta-description, avoiding Flash technology and the breadcrumb trail. These factors worked best in Concrete5 which proved to be the most search engine friendly CMS platform.

The results of this thesis can be used for choosing a CMS for small and medium sized companies. The search engine friendly CMS can help companies to improve their visibility in search results with less spent resources. Frugal Ltd. will use the results of this thesis as an educational material for customer consultation and when choosing a new CMS platform for its most important website Tarkkamarkka.com.