# How to use LangChain with Subconscious

> To use LangChain with Subconscious, create a `ChatOpenAI` model with `base_url="https://api.subconscious.dev/v1"`, `model="subconscious/glm-5.3-marathon"` and your Subconscious API key, then pass it to `create_agent`. Your LangChain agent runs on GLM-5.3 Marathon through the OpenAI-compatible Subconscious API.

Canonical page: https://www.subconscious.dev/agents/frameworks/langchain
Category: [Frameworks](https://www.subconscious.dev/agents/frameworks)
Last verified: 2026-09-30
LangChain: https://docs.langchain.com/oss/python/langchain/overview
Source: https://github.com/langchain-ai/langchain

## Before you start

- Python 3.10+
- A Subconscious account and API key

## Set up LangChain

### 1. Install LangChain

Install the framework and its OpenAI-compatible client.

```bash
pip install -U langchain langchain-openai
```

### 2. Create a Subconscious API key

Sign in at https://platform.subconscious.dev, create an API key, and export it so the tool can read it.

```bash
export SUBCONSCIOUS_API_KEY="your_key"
```

### 3. Point it at Subconscious

create_agent is LangChain's v1 agent API. use_responses_api=False keeps ChatOpenAI on Chat Completions, which is the OpenAI format Subconscious serves.

```python
import os
from langchain.agents import create_agent
from langchain_openai import ChatOpenAI

model = ChatOpenAI(
    model="subconscious/glm-5.3-marathon",
    base_url="https://api.subconscious.dev/v1",
    api_key=os.environ["SUBCONSCIOUS_API_KEY"],
    use_responses_api=False,
)

def get_weather(city: str) -> str:
    """Get the weather for a city."""
    return f"It's always sunny in {city}."

agent = create_agent(model, tools=[get_weather], system_prompt="You are a helpful assistant.")
result = agent.invoke({"messages": [{"role": "user", "content": "What's the weather in SF?"}]})
print(result["messages"][-1].content)
```

### 4. Run it

Run the script.

```bash
python agent.py
```

## Connection details

- OpenAI-compatible base URL: https://api.subconscious.dev/v1
- Anthropic-compatible base URL: https://api.subconscious.dev
- API key: From subc login or the Subconscious dashboard
- Model: subconscious/glm-5.3-marathon
- Multimodal, high-throughput model: subconscious/deepseek-v4.1-flash-marathon

Full API reference: https://docs.subconscious.dev

## Frequently asked questions

### Which Subconscious model should I use with LangChain?

Start with subconscious/glm-5.3-marathon, an open frontier coding model built for long agent runs. subconscious/deepseek-v4.1-flash-marathon is a cheaper, high-throughput alternative that also takes image input. Use the full model ID, including the subconscious/ prefix.

### Is LangChain on Subconscious OpenAI- or Anthropic-compatible?

This guide connects LangChain through the OpenAI-compatible Subconscious API. Subconscious serves both formats: OpenAI Chat Completions at https://api.subconscious.dev/v1 and Anthropic Messages at https://api.subconscious.dev.

### How is LangChain usage on Subconscious billed?

Per token by default, with no commitment. Heavy users can switch to a monthly token plan: a fixed price for a large daily token allowance shared across your team.