Unlike Slack, it is entirely free and you can view channels as a guest without mandatory registration or invitation. There are web, desktop and mobile clients for it.
There is native voice chat support, something Slack doesn't offer.
|Transhumanism||transhumanism.chat||The network has been created by Carsten Kolassa and has the potential to be good generic transhumanist chat network.|
|Healthspan||Life extension and healthspan advocacy and activism. Features a regular voice chat group.|
|Lifespan.io||Life Extension Advocacy Foundation||Life extension advocacy and activism|
|Mind Uploading||Lifetimes Infinity||Mind uploading discussion|
|Artificial Intelligence||AI discussion|
|Scientific Transhumanism||Project hub from Carla Parsons|
|TechnoLibertarians||Technolibertarianism||Chat from Mike Lorrey (Inactive)|
|Futurology||Endorsed by r/Futurology/|