LiteLLM

LiteLLM is an open-source LLM gateway that proxies requests to more than 100 different large language model providers through a single, OpenAI-compatible interface, so a team only has to integrate against one API format regardless of which underlying model they call. It's built for platform teams and enterprises that need to manage authentication, load balancing, spend tracking, and rate limiting across many LLM providers at once. It includes built-in fallbacks if a provider fails, virtual keys and team-level access management, and logging integrations with observability tools like Langfuse, Arize Phoenix, and Langsmith. The open-source version is free; the Enterprise tier is quote-based and adds custom SLAs, JWT authentication, SSO, and audit logs.