Using OpenRouter With LangChain: ChatOpenRouter Setup Guide

You want to add OpenRouter’s 400+ models to your existing LangChain app without rebuilding anything. The integration now has a dedicated package: langchain-openrouter on PyPI and @langchain/openrouter on npm, but many older guides still teach the ChatOpenAI plus base_url override. This guide covers the current path. When you point a LangChain chain at ChatOpenRouter, our routing layer handles provider load balancing, outage avoidance, and cross-provider failover automatically. Your chain code never sees the retry, and an incomplete request doesn’t cost you anything. LangChain’s docs cover the parameters; this guide also covers the routing behavior behind them. Get a working model call in three steps: install, authenticate, invoke. OpenRouter is a model router behind one OpenAI-compatible API: one endpoint, 400+ models, 70+ providers. ChatOpenRouter slots into any chain or agent like any other LangChain chat model. The model string is the only OpenRouter-specific piece. Install…