Create Chat Completion

# Public api users: use https://api.blackbox.ai/chat/completions
curl -X POST https://enterprise.blackbox.ai/chat/completions \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
    "model": "blackboxai/openai/gpt-5.5",
    "messages": [
        {
            "role": "user",
            "content": "What is the capital of France?"
        }
    ],
    "temperature": 0.7,
    "max_tokens": 256,
    "stream": false
}'

const API_KEY = "YOUR_API_KEY";
// Public api users: use "https://api.blackbox.ai/chat/completions"
const API_URL = "https://enterprise.blackbox.ai/chat/completions";

const data = {
    "model": "blackboxai/openai/gpt-5.5",
    "messages": [
        {
            "role": "user",
            "content": "What is the capital of France?"
        }
    ],
    "temperature": 0.7,
    "max_tokens": 256,
    "stream": false
};

const response = await fetch(API_URL, {
    method: 'POST',
    headers: {
        'Authorization': `Bearer ${API_KEY}`,
        'Content-Type': 'application/json'
    },
    body: JSON.stringify(data)
});

const responseData = await response.json();
console.log(responseData);

import requests

API_KEY = "YOUR_API_KEY"
# Public api users: use "https://api.blackbox.ai/chat/completions"
API_URL = "https://enterprise.blackbox.ai/chat/completions"

headers = {
  "Authorization": f"Bearer {API_KEY}",
  "Content-Type": "application/json"
}

data = {
    "model": "blackboxai/openai/gpt-5.5",
    "messages": [
        {
            "role": "user",
            "content": "What is the capital of France?"
        }
    ],
    "temperature": 0.7,
    "max_tokens": 256,
    "stream": False
}

response = requests.post(API_URL, headers=headers, json=data)
print(response.json())

{
  "id":"gen-...",
  "created":1757140020,
  "model":"blackboxai/openai/gpt-5.5",
  "object":"chat.completion",
  "system_fingerprint":"None",
  "choices":[
    {
      "finish_reason":"stop",
      "index":0,
      "message":{
        "content":"The capital of France is Paris.",
        "role":"assistant",
        "tool_calls":"None",
        "function_call":"None"
      },
      "provider_specific_fields":{
        "native_finish_reason":"stop"
      }
    }
  ],
  "usage":{
    "completion_tokens":7,
    "prompt_tokens":14,
    "total_tokens":21,
    "completion_tokens_details":{
      "accepted_prediction_tokens":"None",
      "audio_tokens":"None",
      "reasoning_tokens":0,
      "rejected_prediction_tokens":"None"
    },
    "prompt_tokens_details":{
      "audio_tokens":0,
      "cached_tokens":0
    }
  },
  "provider":"OpenAI"
}

POST

chat

completions

# Public api users: use https://api.blackbox.ai/chat/completions
curl -X POST https://enterprise.blackbox.ai/chat/completions \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
    "model": "blackboxai/openai/gpt-5.5",
    "messages": [
        {
            "role": "user",
            "content": "What is the capital of France?"
        }
    ],
    "temperature": 0.7,
    "max_tokens": 256,
    "stream": false
}'

const API_KEY = "YOUR_API_KEY";
// Public api users: use "https://api.blackbox.ai/chat/completions"
const API_URL = "https://enterprise.blackbox.ai/chat/completions";

const data = {
    "model": "blackboxai/openai/gpt-5.5",
    "messages": [
        {
            "role": "user",
            "content": "What is the capital of France?"
        }
    ],
    "temperature": 0.7,
    "max_tokens": 256,
    "stream": false
};

const response = await fetch(API_URL, {
    method: 'POST',
    headers: {
        'Authorization': `Bearer ${API_KEY}`,
        'Content-Type': 'application/json'
    },
    body: JSON.stringify(data)
});

const responseData = await response.json();
console.log(responseData);

import requests

API_KEY = "YOUR_API_KEY"
# Public api users: use "https://api.blackbox.ai/chat/completions"
API_URL = "https://enterprise.blackbox.ai/chat/completions"

headers = {
  "Authorization": f"Bearer {API_KEY}",
  "Content-Type": "application/json"
}

data = {
    "model": "blackboxai/openai/gpt-5.5",
    "messages": [
        {
            "role": "user",
            "content": "What is the capital of France?"
        }
    ],
    "temperature": 0.7,
    "max_tokens": 256,
    "stream": False
}

response = requests.post(API_URL, headers=headers, json=data)
print(response.json())

{
  "id":"gen-...",
  "created":1757140020,
  "model":"blackboxai/openai/gpt-5.5",
  "object":"chat.completion",
  "system_fingerprint":"None",
  "choices":[
    {
      "finish_reason":"stop",
      "index":0,
      "message":{
        "content":"The capital of France is Paris.",
        "role":"assistant",
        "tool_calls":"None",
        "function_call":"None"
      },
      "provider_specific_fields":{
        "native_finish_reason":"stop"
      }
    }
  ],
  "usage":{
    "completion_tokens":7,
    "prompt_tokens":14,
    "total_tokens":21,
    "completion_tokens_details":{
      "accepted_prediction_tokens":"None",
      "audio_tokens":"None",
      "reasoning_tokens":0,
      "rejected_prediction_tokens":"None"
    },
    "prompt_tokens_details":{
      "audio_tokens":0,
      "cached_tokens":0
    }
  },
  "provider":"OpenAI"
}

Headers

string

required

API Key of the from Bearer <api_key>, you can get it from here.

On an Enterprise plan? Just use enterprise.blackbox.ai instead of api.blackbox.ai for your endpoint.

Request

string

required

The model ID to use. See the Chat Models page

array

required

Array of message objects containing the conversation history.

Show Message Object

string

required

The role of the message author. One of system, user, assistant, or tool.

string | array

The content of the message. Can be a string or array of content parts for multimodal inputs.

string

An optional name for the participant. Provides the model information to differentiate between participants of the same role.

string

For tool messages, the ID of the tool call this message is responding to.

array

Alternate list of models for routing overrides.

object

Preferences for provider routing.

boolean

Enable streaming of results via Server-Sent Events.

integer

Maximum number of tokens to generate (range: [1, context_length)).

number

Sampling temperature (range: [0, 2]).

integer

Seed for deterministic outputs.

number

Top-p sampling value (range: (0, 1]).

integer

Top-k sampling value (range: [1, Infinity)).

number

Frequency penalty (range: [-2, 2]).

number

Presence penalty (range: [-2, 2]).

number

Repetition penalty (range: (0, 2]).

object

Mapping of token IDs to bias values.

integer

Number of top log probabilities to return.

number

Minimum probability threshold (range: [0, 1]).

number

Alternate top sampling parameter (range: [0, 1]).

array

Stop sequences - generation will stop if any of these strings are encountered.

array

Tool definitions following OpenAI’s tool calling format.

Show Tool Object

string

Type of tool, typically function.

object

Function definition.

Show Function Definition

string

Name of the function.

string

Description of what the function does.

object

JSON Schema object defining the function parameters.

string | object

Controls which (if any) tool is called by the model.

none - Model will not call any tool
auto - Model can pick between generating a message or calling tools
required - Model must call one or more tools
Or specify a particular tool via {"type": "function", "function": {"name": "function_name"}}

object

Enforce structured output format.

string

A stable identifier for your end-users. Used to help detect and prevent abuse.

Response

string

Unique identifier for the chat completion.

integer

Unix timestamp when the completion was created.

string

The model used for the completion.

string

Object type, always chat.completion or chat.completion.chunk for streaming.

string | null

System fingerprint for the model configuration.

array

Array of completion choices.

Show Choice Object

string

Reason the generation stopped. Options: stop, length, content_filter, tool_calls, error.

integer

Index of the choice in the list.

object

The generated message.

Show Message Object

string | null

The generated content.

string

Role of the message author, typically assistant.

string | null

Raw reasoning text when reasoning tokens are enabled and not excluded. Contains the model’s step-by-step thinking process.

array | null

Structured reasoning information containing detailed reasoning blocks. Used for preserving reasoning context across multiple API calls.

Show Reasoning Detail Object

string

Type of reasoning detail. Options: reasoning.summary, reasoning.encrypted, reasoning.text.

string | null

Unique identifier for the reasoning detail.

string

Format of the reasoning detail. Options: unknown, openai-responses-v1, xai-responses-v1, anthropic-claude-v1.

number

Sequential index of the reasoning detail.

string

High-level summary of reasoning process (for reasoning.summary type).

string

Raw reasoning text (for reasoning.text type).

string

Encrypted reasoning data (for reasoning.encrypted type).

string | null

Optional signature for verification (for reasoning.text type).

array | null

Tool calls made by the assistant.

Show Tool Call Object

string

Unique identifier for the tool call.

string

Type of tool, typically function.

object

The function call details.

Show Function Object

string

Name of the function being called.

string

JSON string of arguments for the function.

array | null

Annotations containing source citations and references. Available when using models with web search capabilities like blackbox-search.

Show Annotation Object

string

Type of annotation. Currently supports url_citation.

object

Citation information for web sources.

Show URL Citation Object

string

The URL of the cited source.

string

The title of the web page or article.

string

Excerpt or summary of the content from the source (if available).

integer

The character index where the citation begins in the message content.

integer

The character index where the citation ends in the message content.

object | null

Deprecated function call field (use tool_calls instead).

object

Provider-specific response fields.

Show Provider Specific Fields

string

Raw finish reason from the underlying provider.

object

Token usage information.

Show Usage Object

integer

Number of tokens in the completion.

integer

Number of tokens in the prompt.

integer

Total number of tokens used (prompt + completion).

object

Detailed breakdown of completion tokens.

Show Completion Tokens Details

integer | null

Number of accepted prediction tokens.

integer | null

Number of audio tokens in the completion.

integer

Number of reasoning/thinking tokens used.

integer | null

Number of rejected prediction tokens.

object

Detailed breakdown of prompt tokens.

Show Prompt Tokens Details

integer

Number of audio tokens in the prompt.

integer

Number of cached tokens used from previous requests.

string

The provider that served the request.

# Public api users: use https://api.blackbox.ai/chat/completions
curl -X POST https://enterprise.blackbox.ai/chat/completions \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
    "model": "blackboxai/openai/gpt-5.5",
    "messages": [
        {
            "role": "user",
            "content": "What is the capital of France?"
        }
    ],
    "temperature": 0.7,
    "max_tokens": 256,
    "stream": false
}'

const API_KEY = "YOUR_API_KEY";
// Public api users: use "https://api.blackbox.ai/chat/completions"
const API_URL = "https://enterprise.blackbox.ai/chat/completions";

const data = {
    "model": "blackboxai/openai/gpt-5.5",
    "messages": [
        {
            "role": "user",
            "content": "What is the capital of France?"
        }
    ],
    "temperature": 0.7,
    "max_tokens": 256,
    "stream": false
};

const response = await fetch(API_URL, {
    method: 'POST',
    headers: {
        'Authorization': `Bearer ${API_KEY}`,
        'Content-Type': 'application/json'
    },
    body: JSON.stringify(data)
});

const responseData = await response.json();
console.log(responseData);

import requests

API_KEY = "YOUR_API_KEY"
# Public api users: use "https://api.blackbox.ai/chat/completions"
API_URL = "https://enterprise.blackbox.ai/chat/completions"

headers = {
  "Authorization": f"Bearer {API_KEY}",
  "Content-Type": "application/json"
}

data = {
    "model": "blackboxai/openai/gpt-5.5",
    "messages": [
        {
            "role": "user",
            "content": "What is the capital of France?"
        }
    ],
    "temperature": 0.7,
    "max_tokens": 256,
    "stream": False
}

response = requests.post(API_URL, headers=headers, json=data)
print(response.json())

{
  "id":"gen-...",
  "created":1757140020,
  "model":"blackboxai/openai/gpt-5.5",
  "object":"chat.completion",
  "system_fingerprint":"None",
  "choices":[
    {
      "finish_reason":"stop",
      "index":0,
      "message":{
        "content":"The capital of France is Paris.",
        "role":"assistant",
        "tool_calls":"None",
        "function_call":"None"
      },
      "provider_specific_fields":{
        "native_finish_reason":"stop"
      }
    }
  ],
  "usage":{
    "completion_tokens":7,
    "prompt_tokens":14,
    "total_tokens":21,
    "completion_tokens_details":{
      "accepted_prediction_tokens":"None",
      "audio_tokens":"None",
      "reasoning_tokens":0,
      "rejected_prediction_tokens":"None"
    },
    "prompt_tokens_details":{
      "audio_tokens":0,
      "cached_tokens":0
    }
  },
  "provider":"OpenAI"
}

​Headers

​Request

​Response

Headers

Request

Response