What was twitch.com written in?

Question

Programming languages

Is the site written in node.js or something else?

Answer 1

What will this information give you? There is no concept written in node.js, there are technology stacks that are used. Platform, frameworks, design patterns, load distribution methods, etc. All of these stacks are different.
Moreover, absolutely any task can be solved using different sets of technologies. In fact, the choice of stack depends only on the experience of people who start writing a service. Over time, as the project develops, this set of technologies can be partially changed to a more suitable one, that's all.
So if you want to write your service, write in the language and technology that you know best.