> ## Documentation Index > Fetch the complete documentation index at: https://docs.aihubmax.com/llms.txt > Use this file to discover all available pages before exploring further. # OpenAI Format - Simple Chat > - Generic simple Chat Completions API reference for all OpenAI-compatible models - Minimal parameters for quick start - Text conversations: single or multi-turn context - System prompts: customize AI role and behavior - Supports streaming and non-streaming responses ## OpenAPI ````yaml openapi/en/openai-format-simple-chat.json POST /v1/chat/completions openapi: 3.1.0 info: title: OpenAI Format - Simple Chat version: '1.0' servers: - url: https://api.aihubmax.com security: - BearerAuth: [] paths: /v1/chat/completions: post: tags: - Text Series > OpenAI Format summary: OpenAI Format - Simple Chat description: > - Generic simple Chat Completions API reference for all OpenAI-compatible models - Minimal parameters for quick start - Text conversations: single or multi-turn context - System prompts: customize AI role and behavior - Supports streaming and non-streaming responses operationId: openai-format-simple-chat requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/SimpleChatRequest' examples: single-turn: summary: Single Turn description: Basic single-turn Q&A value: model: gpt-5.4 messages: - role: user content: Explain quantum computing in one sentence multi-turn: summary: Multi-turn description: Multi-turn conversation with context value: model: gpt-5.4 messages: - role: system content: You are a professional fitness coach - role: user content: I want to lose fat and can exercise 3 days per week - role: assistant content: >- Great! For a 3-day fat loss plan, I recommend full-body strength training combined with HIIT. Do you have any prior fitness experience? - role: user content: Some basics - I can do push-ups and squats streaming: summary: Streaming description: Enable streaming for real-time content generation value: model: gpt-5.4 messages: - role: user content: Write a short poem about spring stream: true with-image: summary: With Image description: Send an image for model analysis (vision) value: model: gpt-5.4 messages: - role: user content: - type: text text: What's in this image? Please describe in detail - type: image_url image_url: url: >- https://upload.wikimedia.org/wikipedia/commons/thumb/3/3a/Cat03.jpg/1200px-Cat03.jpg responses: '200': $ref: '#/components/responses/ChatCompletionSuccess' '400': $ref: '#/components/responses/BadRequest' '401': $ref: '#/components/responses/Unauthorized' '402': $ref: '#/components/responses/PaymentRequired' '403': $ref: '#/components/responses/Forbidden' '429': $ref: '#/components/responses/TooManyRequests' '500': $ref: '#/components/responses/InternalServerError' components: schemas: SimpleChatRequest: type: object required: - model - messages properties: model: type: string description: Model name, e.g. gpt-5.4, deepseek-chat, claude-sonnet-4-6, etc. example: gpt-5.4 messages: type: array description: List of messages in the conversation items: type: object required: - role - content properties: role: type: string description: Role of the message sender enum: - system - user - assistant content: type: string description: Content of the message stream: type: boolean description: Whether to stream the response default: false temperature: type: number description: Sampling temperature (0-2) minimum: 0 maximum: 2 max_tokens: type: integer description: Maximum number of tokens to generate top_p: type: number description: Nucleus sampling parameter (0-1) minimum: 0 maximum: 1 ChatCompletionResponse: type: object properties: id: type: string description: Unique completion ID example: chatcmpl-abc123 object: type: string description: Object type enum: - chat.completion created: type: integer description: Creation timestamp example: 1757165031 model: type: string description: Model used choices: type: array items: type: object properties: index: type: integer description: Choice index example: 0 message: type: object properties: role: type: string example: assistant content: type: string example: Hello! How can I help you today? finish_reason: type: string description: Reason the generation stopped enum: - stop - length - content_filter example: stop usage: type: object description: Token usage statistics properties: prompt_tokens: type: integer description: Number of tokens in the prompt example: 10 completion_tokens: type: integer description: Number of tokens in the completion example: 50 total_tokens: type: integer description: Total number of tokens used example: 60 ErrorResponse400: type: object properties: error: type: object properties: message: type: string example: Invalid request parameters type: type: string example: invalid_request_error ErrorResponse401: type: object properties: error: type: object properties: message: type: string example: Invalid API key type: type: string example: authentication_error ErrorResponse403: type: object properties: error: type: object properties: message: type: string example: Access denied type: type: string example: permission_error ErrorResponse429: type: object properties: error: type: object properties: message: type: string example: Rate limit exceeded type: type: string example: rate_limit_error ErrorResponse500: type: object properties: error: type: object properties: message: type: string example: Internal server error type: type: string example: server_error responses: ChatCompletionSuccess: description: Chat completion response content: application/json: schema: $ref: '#/components/schemas/ChatCompletionResponse' BadRequest: description: Bad Request content: application/json: schema: $ref: '#/components/schemas/ErrorResponse400' Unauthorized: description: Unauthorized content: application/json: schema: $ref: '#/components/schemas/ErrorResponse401' PaymentRequired: description: Insufficient balance content: application/json: schema: $ref: '#/components/schemas/ErrorResponse400' Forbidden: description: Forbidden content: application/json: schema: $ref: '#/components/schemas/ErrorResponse403' TooManyRequests: description: Too Many Requests content: application/json: schema: $ref: '#/components/schemas/ErrorResponse429' InternalServerError: description: Internal Server Error content: application/json: schema: $ref: '#/components/schemas/ErrorResponse500' securitySchemes: BearerAuth: type: http scheme: bearer description: | ## All APIs require Bearer Token authentication ## Add to request header: `Authorization: Bearer YOUR_API_KEY` ````