Here are the most popular programming languages, databases and software development tools from "Ask HN: Who is hiring? (April 2017)" discussion thread. You can read full thread with comments here. If you're not familiar with the concept of this thread you can read more about it on our blog here or on Hacker News' pages here.
Disclaimer: You are looking at only one source - the "Who is Hiring" thread from Hacker News. While the thread itself is a pretty good source of information, it tends to focus mostly on startup part of the entire IT industry. Any attempts to extrapolate trends presented here to the industry as a whole can be slightly misleading.