Crowdsourcing has been made possible thanks to the evolution of information and communication technology which, in turn, supports innovation and development of organizations. In cultural heritage crowdsourcing is a continuation of a longstanding tradition of inviting the public to contribute on a volunteer basis. This form of online engagement is also a promising tool to enhance the sense of civic responsibility for heritage. The article looks at crowdsourcing as a digital participation practice in cultural heritage. It investigates the case of the Polish Open Monuments crowdsourcing platform. It is an open project with a focus on refining description about historical sites in Poland and Polish historical sites abroad. The paper starts with the introduction of the crowdsourcing notion in the digital era. Then it looks at the organisational aspects of Open Monuments. Having offered an overview of the main issues regarding this paper the next sections offer the examination of the performance of the so called crowds and the analysis of financial implications of crowdsourcing in the nonprofit environment.