Kratos is a production-grade Go microservices framework designed for cloud-native applications. It provides a unified transport layer supporting both HTTP (gorilla/mux) and gRPC, with a composable middleware chain for cross-cutting concerns like logging, tracing, authentication, rate limiting, and circuit breaking. The framework is protobuf-first: service definitions are written in proto files, and code generators (protoc-gen-go-http, protoc-gen-go-errors) produce HTTP stubs and structured error types. It includes a pluggable configuration system with support for multiple sources (file, etcd, consul, nacos, apollo, kubernetes, polaris), a service registry abstraction with implementations for etcd, consul, nacos, eureka, zookeeper, kubernetes, polaris, and others, and a load balancing selector with algorithms like random, weighted round-robin, and power of two choices (p2c). Observability is integrated via OpenTelemetry (tracing, metrics, logging) and Sentry error tracking. The CLI tool `kratos` scaffolds new projects, manages proto generation, and handles upgrades. The architecture is modular: core packages are minimal and extensible, with contrib packages as separate Go modules. The codebase demonstrates strong engineering practices, clean interfaces, and well-tested core components.