LangChain
Most widely used framework for building LLM applications. Chains, agents, RAG pipelines, and deep integrations with 300+ tools.
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).