Enable JSON mode ↗

wandb guide intermediate structured-output configuration

Summary: How to use JSON mode with W&B Inference

Original Documentation

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How to use JSON mode with W&B Inference

Enabling JSON mode instructs the model to return the response in a valid JSON format. However, the response’s schema may not be consistent or adhere to a particular structure. For consistent structured JSON responses, we recommend using structured output when possible.

To enable JSON mode, specify it as the “response_format” in the request:

    import json
    import openai

    client = openai.OpenAI(
        base_url='https://api.inference.wandb.ai/v1',
        api_key="<your-api-key>",  # Create an API key at https://wandb.ai/settings
    )

    response = client.chat.completions.create(
        model="openai/gpt-oss-20b",
        messages=[
            {"role": "system", "content": "You are a helpful assistant that outputs JSON."},
            {"role": "user", "content": "Give me a list of three fruits with their colors."},
        ],
        response_format={"type": "json_object"}  # This enables JSON mode
    )

    content = response.choices[0].message.content
    parsed = json.loads(content)
    print(parsed)
    ```
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```bash
    curl https://api.inference.wandb.ai/v1/chat/completions \
      -H "Content-Type: application/json" \
      -H "Authorization: Bearer <your-api-key>" \
      -d '{
        "model": "openai/gpt-oss-20b",
        "messages": [
            {"role": "system", "content": "You are a helpful assistant that outputs JSON."},
            {"role": "user", "content": "Give me a list of three fruits with their colors."},
        ],
        "response_format": {"type": "json_object"}
      }'
    ```
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Link last verified June 7, 2026. View original ↗

Source: Weights & Biases Docs

Link last verified: 2026-03-04