Tygem www.tygemgo.com, also known as Tygem Baduk or TygemGo or Tygem Global, is an online Go server owned by South Korean company TongYang Online. It is used by many Go players around the workd and especially in South Korea, China and Japan. It usually has several thousand players playing online at a time and the site claims that over 500 professional Go players use the service.
The interface is excellent and a kyu or dan rating is assigned to a player depending on progress. There is a bot for playing against in place of human opponents. There is also a smartphone application for Tygem Baduk. While the site supports the English language, the audio announcements on the site including the Byo Yomi countdown, are in Korean.