Unknown Analytics is fully open source, check the code source here. Some things has been changed in between, we will try to update all information about all the application component. Check the code source here which contains the server code and the the client sdk.
Behind this website, there are a lot of awesome tools and framework that we use to bring you our services.
Despite what the web industry says about RoR, we still love this fantastic framework and all it's ecosystem.
We have worked and still working with vanilla js, jquery, angular, react but when we should pick one, it is absolutely vue.js