> ## Documentation Index
> Fetch the complete documentation index at: https://agno-v2-docs-scavio-google-v2.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Fallback Routing

> Configure ordered OpenRouter fallback models for unavailable primary routes.

Model fallback example using OpenRouter with the Responses API.

```python fallback.py theme={null}
"""Model fallback example using OpenRouter with the Responses API.

This demonstrates using fallback models with OpenRouter's dynamic model routing.
If the primary model fails due to rate limits, timeouts, or unavailability,
OpenRouter will automatically try the fallback models in order.

Requirements:
- Set OPENROUTER_API_KEY environment variable
"""

from agno.agent import Agent
from agno.models.openrouter import OpenRouterResponses

# ---------------------------------------------------------------------------
# Create Agent
# ---------------------------------------------------------------------------

agent = Agent(
    model=OpenRouterResponses(
        id="openai/gpt-oss-20b",
        # Fallback models if primary fails
        models=[
            "openai/gpt-oss-20b",
            "openai/gpt-4o",
        ],
    ),
    markdown=True,
)

agent.print_response("Write a haiku about coding", stream=True)

# ---------------------------------------------------------------------------
# Run Agent
# ---------------------------------------------------------------------------

if __name__ == "__main__":
    pass
```

## Run the Example

<Steps>
  <Snippet file="create-venv-step.mdx" />

  <Step title="Install dependencies">
    ```bash theme={null}
    uv pip install -U agno openai
    ```
  </Step>

  <Step title="Export your OpenRouter API key">
    <CodeGroup>
      ```bash Mac/Linux theme={null}
      export OPENROUTER_API_KEY="your_openrouter_api_key_here"
      ```

      ```bash Windows theme={null}
      $Env:OPENROUTER_API_KEY="your_openrouter_api_key_here"
      ```
    </CodeGroup>
  </Step>

  <Step title="Run the example">
    Save the code above as `fallback.py`, then run:

    ```bash theme={null}
    python fallback.py
    ```
  </Step>
</Steps>

Full source: [cookbook/90\_models/openrouter/responses/fallback.py](https://github.com/agno-agi/agno/blob/main/cookbook/90_models/openrouter/responses/fallback.py)