KOOK is a voice communication platform operated by Beijing Xiaoyao Yixia Technology Co., Ltd. It offers a different approach from traditional voice calls: communication spaces remain available, so friends can drop in to chat whenever they are ready rather than arranging a call each time. Users can explore servers built around interests such as gaming, music, reading, and foreign-language conversation, or create a server to share with a small group of friends. These spaces support everyday conversation as well as gaming and social activities.

KOOK also provides features aimed at esports and gaming communities. Its listed tools include in-game overlays, voice notifications, an OBS livestreaming plugin, and status prompts that show what users are playing. The service is accessible through a downloadable client and a web version, with an app also promoted on its website. KOOK’s site includes a help center and information on privacy, service terms, and business cooperation.