Semantic Router is a decision-making layer for LLMs and agents that uses semantic vector embeddings to route requests instead of waiting for slow LLM generations. It enables fast, intelligent routing based on the semantic meaning of user queries. The library supports multi-modal data processing and integrates with HuggingFace encoders for local deployment as well as cloud-based LLM options. It is designed to accelerate agent workflows by offloading routing decisions from the LLM to a vector-based routing system.