Happy Coder, also referred to as Happy, is an open-source, free, and self-hostable solution designed to enable remote access, control, and real-time synchronization of Claude Code sessions across multiple devices, including desktop and mobile (iOS, Android, Web). It aims to enhance developer productivity and flexibility by integrating with existing workflows and tools without disruption.

The core methodology of Happy Coder is built upon a three-part distributed architecture that facilitates secure, end-to-end encrypted communication between a local Claude Code environment and remote client devices:

1. CLI Program (happy): This component operates as a command-line interface program on the user's local computer. Its primary function is to initiate and monitor a Claude Code session. It actively observes the activities and output of the Claude Code process. Subsequently, it encrypts this information using end-to-end encryption protocols and transmits the encrypted data stream to a designated Relay Server.
2. Mobile App: Available on iOS, Android, and as a web application, this component runs on the user's remote device. It establishes a secure connection with the Relay Server to receive the encrypted data transmitted from the CLI Program. All display logic and user interface elements for rendering the Claude Code session, including its real-time output and interactive capabilities, reside within this mobile application. It decrypts the incoming data for display to the user.
3. Relay Server: This central component acts as an intermediary or message broker, connecting the CLI Program running on the user's computer with the Mobile App on their remote device. Crucially, the Relay Server does not perform any decryption of the data it handles. It functions solely as a pass-through mechanism, relaying "encrypted blobs" of information between the CLI and the mobile client. This design ensures that the server cannot read or access the content of the user's messages or code, maintaining robust end-to-end encryption and privacy.

Key features of Happy Coder include real-time synchronization of Claude Code sessions, enabling users to pick up coding tasks from any device. It supports multiple active sessions and parallel tasks, allowing developers to manage various projects simultaneously. A significant innovation is its voice coding capability, which extends beyond mere dictation to true voice-to-action functionality, permitting hands-free control, debugging, and project management. The system is designed for zero workflow disruption, seamlessly integrating with existing development environments. It provides smart push notifications for critical events, and crucially, all terminal features, including advanced modes and custom agents, are accessible from mobile devices. The project is open-source (MIT licensed) and free to use, emphasizing community contributions and secure communication through end-to-end encryption.