Hiddify is a cross-platform proxy/VPN client built with Flutter and a Go core (Sing-box). It supports multiple proxy protocols (Vless, Vmess, Reality, TUIC, Hysteria, WireGuard, SSH, etc.), subscription management, per-app proxy, routing rules, chain configuration, and advanced features like Warp, Psiphon, and TLS tricks. The architecture is a Flutter frontend communicating with a Go backend via gRPC/protobuf over a local socket. The app uses Riverpod for state management, drift for local SQLite storage, freezed for immutable models, and go_router for navigation. It has platform-specific native code for Android (Kotlin), iOS/macOS (Swift), Windows (C++), and Linux (C). The codebase is well-organized into feature modules, core infrastructure, and generated protobuf bindings. It is actively maintained with CI/CD pipelines and multi-platform releases, though it contains some commented-out code and generated file churn.