Citizen science, the active participation of interested members of the public in research projects by both experts and newcomers, is becoming increasingly important for biodiversity monitoring and conservation. This development is promoted by the transformative effects of citizen science in the fields of science, education and participation. At the same time, the rapid development of digital technologies (e. g. smartphones and apps) is also driving the emergence of new biodiversity-related citizen science projects and applications. Using active citizen science projects and examples of practical applications, we explain the goals and ways in which digital technologies are currently being integrated into citizen science projects. On the one hand, we look at various reporting platforms for opportunistic biodiversity observations as well as opportunistically organised citizen science projects and crowdsourcing initiatives. On the other hand, we present structured citizen science projects that use digital tools to collect data and train participants. Furthermore, we discuss opportunities, challenges and solutions related to citizen science, digitalisation and nature conservation.