OpenAI API
API access to GPT-5, GPT-5.5, o3/o4 reasoning models, and the Responses API; plus embeddings, image, audio, and Realtime endpoints. The most widely deployed LLM API in production.
Galileo
LLM evaluation platform with evaluation models that run in under 200ms — fast enough to use as production guardrails, not just offline eval. Covers hallucination detection, RAG quality, and safety scoring. Distinct from Galileo AI (the UI design tool).