The Daily.co video call API is designed with both product design thinking and technical engineering prowess in mind. It's aimed at developers and product teams looking to integrate a video calling solution into their products, offering UI-ready calls that remove friction and build user-friendly experiences. The API allows for fast and easy setup, and its pricing formula is simple and competitive. Key design aspects include usability, responsive design, device permissions, camera/mic switching, bandwidth muting, browser support, chat, and more. The API also offers configuration options to cater to different use cases, such as 1-to-1 mentor apps or livestream platforms. A collaborative approach was taken in designing the API, with feedback from beta partners and iterative improvements. The design philosophy prioritizes usability, ease of use, robust feature set, technical stability, security, and more.