Turms is a production-grade, open-source instant messaging engine designed for 100K to 10M concurrent users. The system follows a microservices architecture with two core Java/Spring Boot servers: turms-gateway (handles client connections, authentication, session management, and push) and turms-service (implements business logic for messaging, groups, users, conversations, storage, and admin API). Both servers are built on a reactive stack (Project Reactor, Netty) for non-blocking I/O and high throughput. The platform includes a Vue.js admin UI (turms-admin), multiple client SDKs (JavaScript, Kotlin, Swift, Dart, C++), a Flutter chat demo, and a plugin system for extensibility (anti-spam, push notifications, MinIO storage, Rasa chatbot, LiveKit conferencing). Data is stored in MongoDB (sharded), Redis (session, blocklist, sequence IDs), and optionally Elasticsearch for full-text search. The codebase demonstrates strong engineering practices: custom RPC codecs for cluster communication, a property metadata framework for configuration validation, thread-safe rate limiting, and a well-defined plugin extension point system. While primarily an application, it includes an AI serving module (PaddleOCR) for content moderation, but this is a minor component. The repository is actively maintained with frequent commits, comprehensive CI/CD pipelines, and Terraform deployment scripts.