West African languages are written with alphabets that comprize non classical Latin characters. It is possible to design virtual keyboards which allow the writing of such special characters with a combination of keys. During the last decade, many different virtual keyboards had been created, without any standardization to fix the correspondence between each character and the keys to press to obtain it. We define a grid to evaluate such keyboards and apply it to five virtual keyboards in relation with the five main languages of Niger (Fulfulde, Hausa, Kanuri, Songhai-Zarma, Tamashek), Bambara and Soninke from Mali and Dyoula from Burkina Faso. We conclude hat the African LLACAN keyboard should be recommended in Niger because it covers all the characters used in the alphabets of the main languages of this country, it produces valid Unicode codes and it minimizes the number of keys to be pressed.