The counting tool PHYTOBS allows the counting of phytoplankton with a microscope. It is in conformity with the Utermöhl standard (NF-EN 15204, 2006) relative to counting of phytoplankton with an inverted microscope. In the same way it respects the standard protocol of sampling phytoplankton in water bodies for the application of the WFD (Laplace-Treyture & al., 2009) and can serve also in this optic. Different options and functions permit to synthesize and to export the results in order to create a database. One of the buttons permits to reach the reference taxa list of algae potentially met in France with their phylogeny and for the names considered up to date the SANDRE codification.