LangChain, an agent management startup, has raised $300 million in a Series C round at a $3 billion valuation, led by CapitalG with participation from notable investors. LangChain, an AI agent management startup, has secured a $300 million Series C funding round led by CapitalG, elevating its valuation to $3 billion. LangChain has raised $300 million at a $3 billion valuation.