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Represents a streamed chunk returned when streaming the chat completions API, based on the provided input.
data: {
  "id": "chatcmpl-4b71d12c86d94e719c7e3984a7bb7941",
  "object": "chat.completion.chunk",
  "choices": [
    {
      "index": 0,
      "delta": { "role": "assistant", "content": "This" },
      "finish_reason": null,
      "logprobs": null
    }
  ],
  "usage": null,
  "created": 1726294381
}

data: {
  "id": "chatcmpl-4b71d12c86d94e719c7e3984a7bb7941",
  "object": "chat.completion.chunk",
  "choices": [
    {
      "index": 0,
      "delta": { "content": " is" },
      "finish_reason": null,
      "logprobs": null
    }
  ],
  "usage": null,
  "created": 1726294381
}

...

data: {
  "id": "chatcmpl-4b71d12c86d94e719c7e3984a7bb7941",
  "object": "chat.completion.chunk",
  "choices": [
    {
      "index": 0,
      "delta": {},
      "finish_reason": "stop",
      "logprobs": null
    }
  ],
  "usage": null,
  "created": 1726294383
}

data: {
  "id": "chatcmpl-4b71d12c86d94e719c7e3984a7bb7941",
  "object": "chat.completion.chunk",
  "choices": [],
  "usage": {
    "prompt_tokens": 8,
    "completion_tokens": 4,
    "total_tokens": 12
  },
  "created": 1726294402
}

data: [DONE]
data: {
  "id": "chatcmpl-4b71d12c86d94e719c7e3984a7bb7941",
  "object": "chat.completion.chunk",
  "choices": [
    {
      "index": 0,
      "delta": { "role": "assistant", "content": "This" },
      "finish_reason": null,
      "logprobs": null
    }
  ],
  "usage": null,
  "created": 1726294442
}

...

data: {
  "id": "chatcmpl-4b71d12c86d94e719c7e3984a7bb7941",
  "object": "chat.completion.chunk",
  "choices": [
    {
      "index": 0,
      "delta": {
        "role": "assistant",
        "tool_calls": [
          {
            "index": 0,
            "id": "call_TARbemDG9CFdwuoaQBTRXiYK",
            "type": "function",
            "function": { "name": "func", "arguments": "{\"" }
          }
        ]
      },
      "finish_reason": null,
      "logprobs": null
    }
  ],
  "usage": null,
  "created": 1726294442
}

data: {
  "id": "chatcmpl-4b71d12c86d94e719c7e3984a7bb7941",
  "object": "chat.completion.chunk",
  "choices": [
    {
      "index": 0,
      "delta": {
        "role": "assistant",
        "tool_calls": [
          {
            "index": 0,
            "type": "function",
            "function": { "arguments": "arg" }
          }
        ]
      },
      "finish_reason": null,
      "logprobs": null
    }
  ],
  "usage": null,
  "created": 1726294442
}

...

data: {
  "id": "chatcmpl-4b71d12c86d94e719c7e3984a7bb7941",
  "object": "chat.completion.chunk",
  "choices": [
    {
      "index": 0,
      "delta": {
        "role": "assistant",
        "tool_calls": [
          {
            "index": 0,
            "type": "function",
            "function": { "arguments": "}" }
          }
        ]
      },
      "finish_reason": null,
      "logprobs": null
    }
  ],
  "usage": null,
  "created": 1726294442
}

data: {
  "id": "chatcmpl-4b71d12c86d94e719c7e3984a7bb7941",
  "object": "chat.completion.chunk",
  "choices": [
    {
      "index": 0,
      "delta": {},
      "finish_reason": "tool_calls",
      "logprobs": null
    }
  ],
  "usage": null,
  "created": 1726294442
}

data: {
  "id": "chatcmpl-4b71d12c86d94e719c7e3984a7bb7941",
  "object": "chat.completion.chunk",
  "choices": [],
  "usage": {
    "prompt_tokens": 468,
    "completion_tokens": 59,
    "total_tokens": 527
  },
  "created": 1726294443
}

data: [DONE]
id
string
required
A unique ID of the chat completion.
object
string
required
The object type, which is always set to chat.completion.chunk.
model
string
The model to generate the completion.
choices
object[]
required
usage
object | null
created
integer
required
The Unix timestamp (in seconds) for when the token is sampled.
Last modified on July 8, 2026