Papercups is an open-source customer messaging platform combining an embeddable live chat widget with a shared team inbox, built on the Elixir/Phoenix stack for real-time responsiveness and fault tolerance. It supports replying to conversations from email, SMS, Slack, or Mattermost, and offers React, React Native, and Flutter components for embedding chat directly into apps. The project is now in maintenance mode, meaning it remains usable and self-hostable but is not receiving significant new feature development.