What technology stack do Slack and Hipchat use?
How do Slack and Hipchat handle chat on the server side and client side? What languages do they use?
Whenever I'm curious about the technologies used by certain companies I usually check their job postings.
Slack Application engineer job posting:
Our main tools that we use to build Slack are PHP, MySQL, and Linux
Hipchat is a little more vague. They state throughout several job postings that they use PHP, Python, Redis, MySQL, ElasticSearch, and CouchDB. According to a blog post they use PHP for dynamic web pages, and python to implement a XMPP protocol for chat using Twisted.
So at the core it seems like they rely on a PHP/MySQL stack with some addition of other technologies.
I like to check stackshare.io