Uber works and has 3 types of cars available: economy, comfort and black cab. I love the fact that you can pay cash in Uber, so I don't need to pay in Roubles with my US card and get conversions. Apart from Uber you can use: Gett (nice drivers but more expensive on average), Yandex Taxi (like uber, pretty good), and Wheely - business class cars only. There are a few other players but haven't tried them.