Rasa

Rasa is an open-source conversational AI framework that gives developers complete control over building, training, and deploying AI assistants. Unlike hosted platforms, Rasa runs entirely on your infrastructure, making it the go-to choice for enterprises with strict data privacy, security, or compliance requirements. The framework consists of two main components: Rasa Open Source for building the conversational logic and NLU pipeline, and Rasa Pro (commercial) which adds enterprise features like analytics, role-based access control, and a visual conversation builder called Rasa Studio. Rasa uses a unique approach combining traditional NLU (intent classification, entity extraction) with LLM-powered capabilities, allowing developers to leverage the reliability of structured dialog management alongside the flexibility of large language models. The framework supports CALM (Conversational AI with Language Models), an architecture that uses LLMs for understanding while maintaining deterministic business logic for critical paths. Rasa's training pipeline is fully customizable, supporting custom components, featurizers, and policies. The framework includes built-in support for slot filling, form handling, and complex multi-turn conversations. Rasa assistants can be connected to messaging channels like Slack, Telegram, Facebook Messenger, and custom frontends. The platform has a large open-source community with thousands of contributors and extensive documentation. Rasa Pro adds enterprise features including end-to-end testing, conversation-driven development tools, and production deployment infrastructure. Used by companies like Deutsche Telekom, Adobe, and BMW for production conversational AI deployments.