I'm surprised papercups.io is not evaluated elixir, open source, 2 seats in their free tier. Easy and reliable. (no affiliation)

Here's the repo [0], website [1], and demo [2] for anyone who wants to check us out!

[0] https://github.com/papercups-io/papercups

[1] https://papercups.io/

[2] https://app.papercups.io/demo