# LangChain

Connect → LangChain

# Use AxForge with LangChain

    LangChain builds chains and agents around a
    chat model. Its `ChatOpenAI` class takes a base URL, so an AxForge model drops in wherever a model goes:
    chains, tools, agents, LangGraph.

    **Before you start**

        - An AxForge API key, in the environment variable `AXFORGE_API_KEY`.
        Get one (a minute).

        - Python 3.10 or newer. Run with langchain-openai 1.7.2 (langchain-core 1.6.12) on 2026-10-17.

## Set it up

### Install the OpenAI package for LangChain

```
pip install langchain-openai
```

### Point ChatOpenAI at AxForge

```
import os
from langchain_openai import ChatOpenAI

llm = ChatOpenAI(
    base_url="https://api.axforge.ai/v1",
    api_key=os.environ["AXFORGE_API_KEY"],
    model="qwen3.8-27b-nvfp4",
)
print(llm.invoke("Say hello in five words").content)
```

### Run it

```
python hello.py
```

From here `llm` is a LangChain chat model like any other: `llm.stream(...)`,
    `llm.bind_tools([...])`, or pass it to an agent.

## The settings

        | Argument | Value |  |

        | base_url | https://api.axforge.ai/v1 |  |

        | api_key | your AxForge key |  |

        | model | qwen3.8-27b-nvfp4, glm-5.3-flash or mimo-v2.6-flash |  |

Which model for what: `qwen3.8-27b-nvfp4` is the
    everyday default and reads images, `glm-5.3-flash` thinks before it answers,
    `mimo-v2.6-flash` is the fastest. All three can call tools.

## Check that it works

    The script prints an answer. The call shows in the console under
    API Keys → Recent calls within a minute.

## When it does not work

      | What you see | What it means | Fix |  |

        | `AuthenticationError`, 401 "Invalid API key. Create one at https://console.axforge.ai/keys." | the key was refused | check `AXFORGE_API_KEY` holds the whole key, or make a new one |  |

        | `KeyError: 'AXFORGE_API_KEY'` | the variable is not set in this terminal | set it as on Get your API key |  |

        | `NotFoundError`, 404 | the base URL has no `/v1` | use `https://api.axforge.ai/v1` |  |

    Test a call says in one click whether a problem is your key,
    your balance or us.

      ← Open WebUI
      LlamaIndex →



Source: https://dev.axforge.ai/docs/connect/langchain/