I don't have a specific stack. I have moved between stacks over the years. Programming languages involved were Java, Scala, Clojure, Python, C, JavaScript (Node.js), Go, R. So the stacks change based on the programming language. The area of technology I work on have more or less been more constant. I work on distributed computing. Like implementing message passing protocols between nodes, writing job schedulers for distributed database systems that can synchronize jobs, and likewise.