one of the big things in matrix is the existence of bridges as a first class citizen. matrix-appservice-slack exists today (and riot.im hosts an instance of it;

one of the big things in matrix is the existence of bridges as a first class citizen. matrix-appservice-slack exists today (and riot.im hosts an instance of it; you can get at it via Manage Integrations in Riot). The catch is that right now it needs to have outgoing/incoming webhooks provisioned on the Slack channel being bridged. We are working on fixing this with a puppeting bridge though - and there are a few other projects like matrix-puppet-slack which also aim to do this already. https://matrix.org/blog/2017/03/11/how-do-i-bridge-thee-let-me-count-the-ways/ https://matrix.org/blog/2017/03/11/how-do-i-bridge-thee-let-... has the gory details.