Decky Loader is an open-source plugin system that extends the Steam Deck's gaming mode interface with community-made plugins and customizations. It functions as a plugin loader that injects JavaScript plugins into the Steam Deck's web-based interface at runtime, enabling real-time appearance and behavior changes without leaving the active gaming session.
The system combines a CORS-bypassing proxy layer that intercepts and modifies HTTP fetch requests from plugins to remove same-origin restrictions, with a Python-to-TypeScript bridge that exposes Python functions as callable TypeScript methods through bidirectional IPC. This allows plugins to make fetch requests to any domain and run Python functions directly from TypeScript React code for extended backend logic. A runtime plugin lifecycle manager handles installation, updates, uninstallation, and reloading through a dedicated menu system that operates entirely within the gaming session.
The platform includes an in-place plugin store browser that embeds a full web view within the Steam Deck's overlay, allowing users to browse, install, and manage plugins without leaving the game interface. Through the UI overlay injection system, users can modify the Steam Deck's interface styling, screen saturation, system sounds, and other appearance settings via community plugins.
