> ## Documentation Index
> Fetch the complete documentation index at: https://docs.neosantara.xyz/llms.txt
> Use this file to discover all available pages before exploring further.

# Structured Outputs

> Constrain AI model responses to strictly adhere to your supplied JSON Schema.

Structured Outputs on `/v1/chat/completions` guarantees that model responses match your provided JSON Schema, eliminating runtime JSON parsing errors in production applications.

<CodeGroup>
  ```python Python (Pydantic / OpenAI SDK) icon="python" theme={"theme":{"light":"ayu-dark","dark":"catppuccin-latte"}}
  from openai import OpenAI
  from pydantic import BaseModel, Field
  import os

  client = OpenAI(
      base_url="https://api.neosantara.xyz/v1",
      api_key=os.environ["NEOSANTARA_API_KEY"]
  )

  class ResearchPaper(BaseModel):
      title: str = Field(description="Title of the paper")
      authors: list[str] = Field(description="List of authors")
      published_year: int = Field(description="Year published")
      summary: str = Field(description="Two-sentence summary")

  completion = client.beta.chat.completions.parse(
      model="deepseek-v4.1-flash",
      messages=[
          {"role": "user", "content": "Extract data from: 'Attention Is All You Need' by Vaswani et al., published in 2017."}
      ],
      response_format=ResearchPaper
  )

  paper = completion.choices[0].message.parsed
  print(f"Title: {paper.title}")
  print(f"Year: {paper.published_year}")
  ```

  ```python Python (Raw JSON Schema) icon="python" theme={"theme":{"light":"ayu-dark","dark":"catppuccin-latte"}}
  from openai import OpenAI
  import os

  client = OpenAI(
      base_url="https://api.neosantara.xyz/v1",
      api_key=os.environ["NEOSANTARA_API_KEY"]
  )

  response = client.chat.completions.create(
      model="deepseek-v4.1-flash",
      messages=[{"role": "user", "content": "Return sample user details."}],
      response_format={
          "type": "json_schema",
          "json_schema": {
              "name": "user_profile",
              "strict": True,
              "schema": {
                  "type": "object",
                  "properties": {
                      "username": {"type": "string"},
                      "email": {"type": "string"},
                      "age": {"type": "integer"}
                  },
                  "required": ["username", "email", "age"],
                  "additionalProperties": False
              }
          }
      }
  )

  print(response.choices[0].message.content)
  ```

  ```bash cURL icon="terminal" theme={"theme":{"light":"ayu-dark","dark":"catppuccin-latte"}}
  curl -X POST https://api.neosantara.xyz/v1/chat/completions \
    -H "Authorization: Bearer $NEOSANTARA_API_KEY" \
    -H "Content-Type: application/json" \
    -d '{
      "model": "deepseek-v4.1-flash",
      "messages": [{"role": "user", "content": "User sample"}],
      "response_format": {
        "type": "json_schema",
        "json_schema": {
          "name": "user",
          "strict": true,
          "schema": {
            "type": "object",
            "properties": {
              "name": {"type": "string"},
              "role": {"type": "string"}
            },
            "required": ["name", "role"],
            "additionalProperties": false
          }
        }
      }
    }'
  ```
</CodeGroup>

## Comparing JSON Mode vs Structured Outputs

| Criteria                | JSON Mode (`type: "json_object"`)                  | Structured Outputs (`type: "json_schema"`)         |
| :---------------------- | :------------------------------------------------- | :------------------------------------------------- |
| **Schema Guarantee**    | Valid JSON syntax, but keys and fields may drift.  | 100% adherence to defined schema, types, and keys. |
| **Prompt Prerequisite** | Requires explicit mention of "JSON" in the prompt. | No prompt prompting required.                      |
| **Strict Enforcement**  | Not supported.                                     | Fully supported (`strict: true`).                  |

## Models Supporting Structured Outputs

| Model                 | Strict Mode Support | Context Window   |
| :-------------------- | :------------------ | :--------------- |
| `deepseek-v4.1-flash` | Yes                 | 1,000,000 tokens |
| `gemini-3.8-flash`    | Yes                 | 1,000,000 tokens |
| `gpt-5.4-mini`        | Yes                 | 128,000 tokens   |

## Next Steps

| Task                      | Guide                                                         |
| :------------------------ | :------------------------------------------------------------ |
| Invoke External Functions | [Function Calling](/en/gateway/chat-completions/tool-calling) |
| Token Streaming           | [Streaming Responses](/en/gateway/chat-completions/streaming) |


## Related topics

- [Chat Completions](/en/gateway/chat-completions.md)
- [Function Calling (Tools)](/en/gateway/chat-completions/tool-calling.md)
- [Pydantic AI](/en/integrations/pydantic-ai.md)
- [Model Catalog](/en/gateway/models.md)