Party Line is an open-source audio chat and collaboration app built using the Daily API, with sample code available for React, iOS, Android, and React Native. The app allows users to create audio rooms and invite friends to join as speakers or listeners, with features such as moderation controls, role management, and user authentication handling. The app's architecture is designed to be modular and extensible, with a focus on simplicity and ease of use. The sample code includes four demo clients, each with its own README file providing platform-specific setup instructions. The project aims to provide a starting point for developers building their own audio chat and collaboration apps, with the goal of making it easy for them to get started without having to reinvent the wheel.