Posting here to make sure people get sent the correct way if they search for the slack channel. Having used slack for over 3 years we are running into some issues, as @avehtari formulated it in the slack environment:
This Slack workspace is using the free plan which has limit of 10k messages. In some channels we have been and still are losing useful information beyond the paywall, SGB checked that we can't get non-profit discount from Slack and regular plan is quite expensive. The suggestion to move to Zulip that provides free plan for free software projects. You can join the Stan Zulip at https://mc-stan.zulipchat.com/join/irkoc4dfqkppddwpni2iomr7/ (related discourse thread at https://discourse.mc-stan.org/t/stan-general-meeting-mar-04-2021-11-am-est/21049/26). It will annoying to move, but I hope many would soon test the Zulip and provide feedback if there are strong reasons to not move.