I remember there's a Slack architecture case study by AWS[0]. I was a little bit surprised that the architecture can hold such huge traffic.

As a comparison, Discord use's tech stack is more niche and cutting edge[1], but they seem to know very well what they are doing.

It's interesting because AWS use Slack's architecture as a case study because it's a little bit mediocre, that their major potential customers can understand and use. I just don't think AWS will ever use Discord's architecture as a case study...

[0] https://aws.amazon.com/solutions/case-studies/slack/ [1] https://blog.discordapp.com/scaling-elixir-f9b8e1e7c29b