LangChain OpenRouter: How to Access 400+ LLMs Through One API Without Rewriting Chains

LangChain + OpenRouter: A Practical Guide to Calling 400+ LLMs Through One API How to integrate OpenRouter’s unified model gateway into your LangChain applications without rewriting your chains. If you’re building AI apps with LangChain, you’ve probably faced the provider dilemma. Lock into OpenAI’s GPT family? Bet on Anthropic’s Claude? Keep a back door open for Google’s Gemini? Every choice means a separate API key, a different parameter schema, and its own failure modes. Worse, when you want to A/B test GPT-4 against Claude, or give your users in China a DeepSeek fallback, nearly every line of your chain code …