Moco is a Java library and standalone server for creating mock HTTP servers, primarily used for integration testing. It supports HTTP/HTTPS, REST, WebSocket, SSE, CORS, proxy with failover/playback, recording/replaying, and template-based responses. Architecture is modular: moco-core provides interfaces and implementations (Netty-based server, request matchers, response handlers), moco-runner adds a CLI for JSON-based configuration and standalone execution, and moco-junit/moco-junit5 provide JUnit integration. The system is configured either via a fluent Java API (central `Moco` static factory) or JSON configuration files, making it easy to stub endpoints in tests or as a standalone mock service. It uses Netty for high-performance HTTP serving, Jackson for JSON processing, Freemarker for templates, and Guava for utilities. The codebase is well-structured with clear separation of concerns, extensive tests, and support for modern protocols like HTTP/2 and WebSocket.