The article analyzes three edit-a-thons of the Spanish version of Wikipedia. These are collective and simultaneous edition events on the free encyclopedia, aimed at improving coverage of gender, local content, and underrepresented groups. The experiences were carried out in Cordoba, Argentina, during 2018 and 2019. The cases are: 1) Edit-a-thon of Latin American Women, Art y Feminism; 2) Educational Edit-a-thon of San Francisco city; 3) Edit-a-thon: Native Communities from the centre of Argentina. We focused on four emerging dimensions: integration of volunteers and institutions, online and offline organization, exploration and recognition of biases, and appropriation of the activity. The results show educational potentialities in this collaborative knowledge building platform. The methodology is the recording of experiences by researchers-participants, together with the use of secondary online sources.