I have worked for a few different companies on top of many stacks including ActionScript 2 and 3, C# (.NET 1.1-3.5, windows desktop and ASP.NET, .NET 4.6 C#/WPF), MS SQL/MariaDB/PostgreSQL, PHP, Java, Python, Cython, C and C++ (and C++-compatible C, and C-compatible C++), Objective C. I've worked on Windows, macOS and Linux (and applications targeting all three.)
My most proficient programming language is Python, which I used (along with Cython/C/C++ extensions) to complete my PhD in physics, in which I produced a new computational geometry algorithm.
I have written a Lisp, made a flash game, published an android app and used OpenGL as a debugger. Now I work for a hardware vendor in Cambridgeshire where I mostly write C#/XAML (although I occasionally use Python there too.)