The basic features included in Overwolf are the same as those provided by the Valve client, with the most striking undoubtedly being the integrated browser and the chat system. Thanks to these services, you can open a browser tab or chat window as you play and still keep the game running. Additionally, Overwolf's chat allows you to sync up your Skype, Facebook, and even Steam accounts.
Beyond these basic features, Overwolf has a proper app store that lets you incorporate lots of additional features. You can choose from music players based on Grooveshark or Spotify as well as specific tools for particular games like World of Warcraft or Day Z.
Another interesting thing is that Overwolf lets you identify all the games you have on your computer that are compatible with it. Its compatibility list includes titles like Smite, Hearthstone, FIFA World, the Assassin's Creed saga, League of Legends, and Robocraft.
Overwolf is a very useful companion app that every gamer should have. It works especially well with some of the biggest free-to-play titles.