The "CoAct for Mental Health" chatbot is a Telegram mobile-based messaging tool to send the microstories written by the Co-Researchers to the Citizen Scientists. Citizen Scientists can answer using buttons and in a structured manner over a long period of time, once or twice every day. The chatbot source code is openly accessible in Creative Commons licence in a Github repository. The chatbot functioning will be showcased in real time by 2 CoResearchers and a member of the promoting team, thus introducing this innovative tool to the conference participants. Using a chatbot for health participatory research has several benefits: the participants can answer the question when it is most convenient for them, thus integrating participation into their daily routines. They can also answer in a private manner and in safe surroundings. The chatbot is also seen as a medium to explore how to increase long-term engagement, which is particularly challenging in Citizen Science projects.