LLMRouter: Unified Infrastructure for Developing, Evaluating, and Deploying LLM Routers

Open-source modular framework that unifies LLM routing as a five-component sequential decision process (context encoders, model encoders, scoring functions, decision rules, learning signals) and ships 16+ routers with the xRouteBench benchmark. Learned routers outperform the strongest fixed-model baseline by 14.6% relatively, and user-conditioned routing consistently improves personalization.