LangChain Integration

LangChain is the leading framework for building applications powered by language models. It provides composable components for chains, agents, RAG, and memory, with support for dozens of LLM providers.

LangChain's ChatOpenAI class supports custom base URLs for OpenAI-compatible endpoints.

Prerequisites

An LLM API account with an API key
LangChain installed or accessible

Setup

Get Your LLM API Key

Log in to your LLM API dashboard
Click Create Key to Start
Copy your new API key immediately — it will only be shown once
Store the key securely (e.g., in a password manager or .env file)

LLM API is an OpenAI-compatible gateway that gives you access to dozens of AI models through a single API key and endpoint.

Configure LLM API in LangChain

Install LangChain:

pip install langchain-openai

Configure:

from langchain_openai import ChatOpenAI
llm = ChatOpenAI(
    model="openai/gpt-4o",
    api_key="your-llm-api-key-here",
    base_url="https://api.llmapi.ai/v1"
)

Or set environment variables:

export OPENAI_API_KEY="your-llm-api-key-here"
export OPENAI_API_BASE="https://api.llmapi.ai/v1"

Test the Integration

Verify that LangChain can successfully communicate with LLM API by sending a test request. All requests will now be routed through LLM API.

All LangChain chains, agents, and tools work seamlessly with LLM API through ChatOpenAI.

Benefits of Using LLM API with LangChain

Multi-Provider Access: Use models from OpenAI, Anthropic, Google, and more through a single API
Cost Control: Track and limit your AI spending with detailed usage analytics
Unified Billing: One account for all providers instead of managing multiple API keys
Caching: Reduce costs with response caching for repeated requests

View all available models on the models page.