We've been using Elixir for our API server from the start. It's a great language and scales really well. We needed to add a websocket API at some point, and now

We've been using Elixir for our API server from the start. It's a great language and scales really well. We needed to add a websocket API at some point, and now it's our channel with most throughput. Phoenix handles it fine, and we're still able to triple the throughput comfortably. The one thing that we struggled with Elixir with is that it's quite hard to find people that know Elixir. For a long time I was the only one doing Elixir in the company, which introduced a bottleneck. That said, when you find someone who knows Elixir they tend to know Elixir (and a bit of infra) quite well.