My primary role is to extend UX team capabilites by developing interactive prototypes to visualize business needs and help validate potential ideas. It is much easier to understand the domain and drive discussions when there is something to show or even try out. At least this way more corner cases are uncovered earlier and can be resolved before the actual development.
I am primarily using HTML5, Angular JS, Angular Material, CSS3, Bower, Grunt, LESS or SASS for frontend development and NodeJS, ExpressJS, MongoDB for the backend. I've also set up Continuous integration to free myself from redundant work and ensure that the latest version is always accessible on heroku.
I know that the work I do is a bit wasteful and not always necessary. On the other hand, I let other team members to do more interesting work than clicking in axure. With a right set of libraries, especially Angular JS - most things are just faster to do in code! Initially used for an attempt to get into game development industry, but now for my own projects that I come up with to stay up-to date with latest technologies.
Latest experience is with xamarin as I was eager to try it out, but last time I checked (possibly long time ago) they didn't have an indie friendly license - apparently they do now!