Open Science (OS) has become a catalyst in shaping research and society in the EU by supporting science in meeting the grand challenges our societies face today. OS shapes the scientific and societal transformation for accountability, transparency and sustainability. One of the OS components is Citizen Science (CS) which has been acknowledged as a pivotal field for the new generation science (see UNESCO’s first draft of the “Recommendation on Open Science”, 2020) and has been growing exponentially the last few years, with hundreds of scientists already leading CS projects and millions of volunteers participating in a increasing number of CS initiatives.