The poster session was organized using the Mattermost server as well. For each poster, a separate chat channel was created, where people could text chat with the presenter. In addition, DFNconf video chat rooms were provided for each poster. Thus, participants could engage with the presenters "face to face" via video chat or asynchronously using the text chat. We believe this approach has several advantages: First, it does not require registration with an external website that might be geoblocked by the local government, e.g. twitter. Second, text chat is very technologically robust, requiring neither a high-speed internet connection nor webcam or microphone. We found that text chat facilitates informal discussions between participants on a level comparable to on-site poster sessions, while in comparison, the video chat rooms we provided were used by far fewer participants. Text chat allowed participants to engage with several presenters at the same time by posting questions in chat, then moving on to another poster while awaiting an answer. The separate chat channels created for each poster on our Mattermost server also allowed presenters to look at other posters when not answering questions without fear of missing any discussion of their own work that might be taking place in their absence. Finally, the chat channels were very convenient for us as organizers to set up and moderate, compared to the effort of setting up multiple video chat rooms and making them easily accessible to all participants. One drawback that occurred in regard to the poster presentation on chat was that very few presenters did not appear. This could be because of a big time difference where the poster presentation did not start until after midnight, e.g., for Asian participants. The Mattermost platform also has an integrated poll feature, and we allowed that all participants of the poster session voted for their three favourite posters per session, awarding the poster prize (sponsored by a scientific book publisher) as a "community prize". Poster presenters were asked to prepare their poster in an aspect ratio of 16:9 for best visibility on a computer screen .