This article looks rather rushed -- the description of Zulip is not accurate, and I suspect that folks working on the other products may feel the same way about how their projects are described.

I lead the Zulip project, and I'd like to clarify that Zulip's free community pricing does not have user limits, either in Cloud or self-hosting. The 10 user limit for free mobile notifications only applies to workplace/business use. Larger communities are encouraged to submit a simple form to get approved for notifications beyond 10 users.

And this complaint seems quite strange:

> Even for self-hosted plans, anything above the free tier requires a zulip.com account for plan management.

How would a paid subscription work without an account for managing it?

This is an important and timely topic, but I wish a more deeply researched article was the one being widely circulated.