The Home Assistant Companion app functions as the mobile gateway to the open-source Home Assistant ecosystem, which positions itself as a privacy-focused alternative to cloud-based smart home platforms. Unlike proprietary solutions, this app connects to a self-hosted instance running on local hardware such as Raspberry Pi or dedicated Home Assistant devices, ensuring data remains within the user's control without mandatory cloud integration. Core functionality centers around providing remote access to the full Home Assistant dashboard, enabling users to monitor and control thousands of compatible devices from major smart home brands. The app supports real-time status updates, automation triggering, and sensor monitoring while maintaining the platform's signature local processing approach. Advanced features include location-based automation using device sensors, notification management, and integration with Android's quick settings tiles for instant device control without fully opening the application. User experience varies significantly based on the underlying Home Assistant configuration, as the app primarily serves as a frontend interface. The clean, responsive design mirrors the web interface's organizational capabilities, allowing users to create customized dashboards with entity cards, maps, and automation controls. Real-world usage patterns show most users employ the app for quick device toggling, checking security camera feeds, and adjusting climate controls while away from home networks via the optional Nabu Casa remote access service. User feedback indicates generally positive experiences with notable specific concerns. Tom Ferrel's January 2025 review initially reflected confusion about the app's companion nature before recognizing its purpose, highlighting potential onboarding clarity issues. Rob S.'s February 2025 praise noted excellent functionality but criticized persistent location notifications that cannot be individually disabled. Ivan Tomasic's January 2024 review praised functionality while questioning the value proposition of the $65/year remote access subscription compared to self-configured alternatives. The app's primary strength lies in its seamless integration with the powerful Home Assistant ecosystem, offering unparalleled device compatibility and local control. Limitations include dependency on user-configured backend systems and occasional notification management frustrations. Ideal for technical users who prioritize privacy and already maintain Home Assistant instances, though less suitable for those seeking out-of-box solutions without technical setup requirements.