Aspia is a comprehensive, cross-platform remote desktop and system administration suite. The codebase is decomposed into four primary components: a **host** (the machine being controlled), a **client** (the controlling machine), a **router** (session brokering and NAT traversal), and a **relay** (traffic forwarding). It supports Windows, Linux, macOS, and Android, with platform-specific implementations for screen capture (DXGI, X11, Wayland/PipeWire, KMS/DRM, Android MediaProjection), audio (WASAPI, PulseAudio, Oboe), input injection, and clipboard integration. The system uses encrypted communication with SRP authentication, X25519 key exchange, and AEAD ciphers (AES-256-GCM, ChaCha20-Poly1305) with key ratcheting. Beyond desktop sharing, it provides file transfer, text chat, remote terminal, task manager, system information collection, and video recording. The client features both a Qt-based desktop GUI and a custom Android UI built with native widgets. The router manages host discovery, two-factor authentication (TOTP), and relay session keys, while the relay handles peer-to-peer forwarding. The codebase is built with CMake, uses protobuf for messaging, and relies on libraries like asio, OpenSSL, libvpx, libyuv, and zstd.