I have worked with Darwinex in some ocassions. They needed re-develop their app and I have worked with them for two month. Then I have worked with them temporarily when they have had a lot of work. Usually, I was in charge about html and sass, working in mustache enviroment and following the atom design metodology. However to start working with them I had to do a test doing a responsive slider with jquery and graphics with D3 that I show it in the gif.