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

# GPT-5.5 Chat

> GPT-5.5 with enhanced general reasoning, coding, and multimodal capabilities

* OpenAI-compatible Chat Completions API
* Select the `gpt-5.5` model via the `model` parameter
* Supports streaming output (SSE)
* Supports multi-turn conversation, system prompts, and vision input

## Authorizations

<ParamField header="Authorization" type="string" required>
  All endpoints require Bearer Token authentication

  Get your API Key from the [API Key Management Page](https://toapis.com/console/token)

  Add to request header:

  ```
  Authorization: Bearer YOUR_API_KEY
  ```
</ParamField>

## Body

<ParamField body="model" type="string" default="gpt-5.5" required>
  모델 name

  Example: `"gpt-5.5"`
</ParamField>

<ParamField body="messages" type="object[]" required>
  List of conversation messages in chronological order

  <Expandable title="messages[n]">
    <ParamField body="role" type="string" required>
      Message role — `system`, `user`, or `assistant`
    </ParamField>

    <ParamField body="content" type="string" required>
      Message content — string or array of content blocks (supports images)
    </ParamField>
  </Expandable>
</ParamField>

<ParamField body="stream" type="boolean" default={false}>
  Whether to enable streaming output (Server-Sent Events)

  * `true`: Stream tokens incrementally
  * `false`: Return the complete response at once
</ParamField>

<ParamField body="max_tokens" type="integer">
  Maximum number of tokens to generate

  Uses the model's default limit when not set
</ParamField>

<ParamField body="temperature" type="number" default={1}>
  Sampling temperature, controls output randomness

  * Range: `0` to `2`
  * Lower values produce more deterministic output; higher values produce more varied output
</ParamField>

<ParamField body="top_p" type="number" default={1}>
  Nucleus sampling probability threshold

  Range: `0` to `1`. It is not recommended to modify both `temperature` and `top_p` at the same time
</ParamField>

<ParamField body="stop" type="string | string[]">
  Stop sequences — generation stops when these strings are encountered

  Maximum 4 stop sequences
</ParamField>

## 응답

<ResponseField name="id" type="string">
  Unique identifier for this request
</ResponseField>

<ResponseField name="object" type="string">
  Object type, always `chat.completion`
</ResponseField>

<ResponseField name="created" type="integer">
  Request creation timestamp (Unix)
</ResponseField>

<ResponseField name="model" type="string">
  The model that was actually used
</ResponseField>

<ResponseField name="choices" type="object[]">
  List of generated results

  * `choices[].message.role`: Message role, always `assistant`
  * `choices[].message.content`: Generated text content
  * `choices[].finish_reason`: Stop reason — `stop` / `length` / `content_filter`
  * `choices[].index`: Result index
</ResponseField>

<ResponseField name="usage" type="object">
  Token usage statistics for this request

  * `usage.prompt_tokens`: Input token count
  * `usage.completion_tokens`: Output token count
  * `usage.total_tokens`: Total token count
</ResponseField>

<RequestExample>
  ```bash cURL theme={null}
  curl --request POST \
    --url https://toapis.com/v1/chat/completions \
    --header 'Authorization: Bearer <token>' \
    --header 'Content-Type: application/json' \
    --data '{
      "model": "gpt-5.5",
      "messages": [
        {
          "role": "user",
          "content": "Hello, please introduce yourself"
        }
      ]
    }'
  ```

  ```bash cURL (Streaming) theme={null}
  curl --request POST \
    --url https://toapis.com/v1/chat/completions \
    --header 'Authorization: Bearer <token>' \
    --header 'Content-Type: application/json' \
    --data '{
      "model": "gpt-5.5",
      "messages": [
        {
          "role": "system",
          "content": "You are a professional code assistant"
        },
        {
          "role": "user",
          "content": "Write a quicksort in Python"
        }
      ],
      "stream": true
    }'
  ```

  ```bash cURL (Vision Input) theme={null}
  curl --request POST \
    --url https://toapis.com/v1/chat/completions \
    --header 'Authorization: Bearer <token>' \
    --header 'Content-Type: application/json' \
    --data '{
      "model": "gpt-5.5",
      "messages": [
        {
          "role": "user",
          "content": [
            {
              "type": "text",
              "text": "What is in this image?"
            },
            {
              "type": "image_url",
              "image_url": {
                "url": "https://www.gstatic.com/webp/gallery/1.jpg"
              }
            }
          ]
        }
      ],
      "max_tokens": 300
    }'
  ```

  ```python Python (openai SDK) theme={null}
  from openai import OpenAI

  client = OpenAI(
      api_key="your-ToAPIs-key",
      base_url="https://toapis.com/v1"
  )

  response = client.chat.completions.create(
      model="gpt-5.5",
      messages=[
          {"role": "user", "content": "Hello, please introduce yourself"}
      ]
  )

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

  ```python Python (Vision Input) theme={null}
  from openai import OpenAI

  client = OpenAI(
      api_key="your-ToAPIs-key",
      base_url="https://toapis.com/v1"
  )

  response = client.chat.completions.create(
      model="gpt-5.5",
      messages=[
          {
              "role": "user",
              "content": [
                  {"type": "text", "text": "What is in this image?"},
                  {
                      "type": "image_url",
                      "image_url": {"url": "https://www.gstatic.com/webp/gallery/1.jpg"}
                  }
              ]
          }
      ],
      max_tokens=300
  )

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

  ```python Python (Streaming) theme={null}
  from openai import OpenAI

  client = OpenAI(
      api_key="your-ToAPIs-key",
      base_url="https://toapis.com/v1"
  )

  stream = client.chat.completions.create(
      model="gpt-5.5",
      messages=[
          {"role": "system", "content": "You are a professional code assistant"},
          {"role": "user", "content": "Write a quicksort in Python"}
      ],
      stream=True
  )

  for chunk in stream:
      if chunk.choices[0].delta.content:
          print(chunk.choices[0].delta.content, end="", flush=True)
  ```

  ```javascript JavaScript (openai SDK) theme={null}
  import OpenAI from "openai";

  const client = new OpenAI({
    apiKey: "your-ToAPIs-key",
    baseURL: "https://toapis.com/v1",
  });

  const response = await client.chat.completions.create({
    model: "gpt-5.5",
    messages: [{ role: "user", content: "Hello, please introduce yourself" }],
  });

  console.log(response.choices[0].message.content);
  ```
</RequestExample>

<ResponseExample>
  ```json 200 theme={null}
  {
    "id": "chatcmpl-abc123",
    "object": "chat.completion",
    "created": 1703884800,
    "model": "gpt-5.5",
    "choices": [
      {
        "index": 0,
        "message": {
          "role": "assistant",
          "content": "Hello! I'm GPT-5.5, the latest model in OpenAI's fifth-generation series. I have enhanced capabilities in reasoning, code generation, and multimodal understanding. How can I help you today?"
        },
        "finish_reason": "stop"
      }
    ],
    "usage": {
      "prompt_tokens": 13,
      "completion_tokens": 42,
      "total_tokens": 55
    }
  }
  ```

  ```json 400 theme={null}
  {
    "error": {
      "code": "invalid_request_error",
      "message": "The 'messages' field is required.",
      "param": "messages",
      "type": "invalid_request_error"
    }
  }
  ```

  ```json 401 theme={null}
  {
    "error": {
      "code": "unauthorized",
      "message": "Invalid API key",
      "type": "authentication_error"
    }
  }
  ```
</ResponseExample>