> ## Documentation Index > Fetch the complete documentation index at: https://docs.apiyi.com/llms.txt > Use this file to discover all available pages before exploring further. # Chat Completions > Online playground for the chat completions endpoint — enter your API Key to send requests and view responses. POST /v1/chat/completions ## OpenAPI ````yaml api-reference/apiyi-openapi-en.yaml POST /v1/chat/completions openapi: 3.1.0 info: title: APIYI - AI Model API description: > OpenAI-compatible AI model API aggregation platform. APIYI uses the OpenAI-compatible format, supporting 400+ mainstream AI models with a single API key. **Authentication**: Add `Authorization: Bearer YOUR_API_KEY` to request headers. **Get API Key**: Visit the [APIYI Console](https://api.apiyi.com/token) to create a token. **Streaming Note**: The Playground does not support streaming response preview. Use an SDK to test streaming output. version: 1.0.0 servers: - url: https://api.apiyi.com description: Primary Endpoint - url: https://vip.apiyi.com description: Backup Endpoint security: - bearerAuth: [] paths: /v1/chat/completions: post: tags: - Chat summary: Chat Completions description: > Core chat interface, compatible with the OpenAI Chat Completions API format. Supports 400+ AI models — just change the `model` parameter to switch between providers, with no other code changes needed. **Supported providers**: OpenAI, Anthropic, Google, xAI, DeepSeek, Alibaba, Moonshot, and more. **Note**: Streaming output (stream: true) cannot be previewed in the Playground. Use an SDK to test. operationId: createChatCompletion requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/ChatCompletionRequest' example: model: gpt-4o messages: - role: system content: You are a helpful assistant. - role: user content: Hello, please introduce yourself. temperature: 0.7 max_tokens: 1000 responses: '200': description: Successfully returned chat completion result content: application/json: schema: $ref: '#/components/schemas/ChatCompletionResponse' example: id: chatcmpl-abc123 object: chat.completion created: 1702855400 model: gpt-4o choices: - index: 0 message: role: assistant content: >- Hello! I'm an AI assistant, happy to help you. I can answer questions, write content, write code, and more. How can I assist you today? finish_reason: stop usage: prompt_tokens: 25 completion_tokens: 42 total_tokens: 67 '400': description: Bad request parameters content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '401': description: Invalid API Key content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '429': description: Rate limit exceeded or insufficient quota content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '500': description: Internal server error content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' components: schemas: ChatCompletionRequest: type: object required: - model - messages properties: model: type: string description: > Model name. APIYI supports 400+ models — just change the model name to switch between providers. examples: - gpt-4o - gpt-4o-mini - gpt-5-chat-latest - claude-sonnet-4-20250514 - claude-opus-4-1-20250805 - claude-3-5-haiku-20241022 - gemini-2.5-pro - gemini-2.5-flash - gemini-2.0-flash - deepseek-r1 - deepseek-v3-0324 - grok-4-0709 - grok-3 - o4-mini - o3 - qwen-max - glm-4-plus messages: type: array description: Array of conversation messages, supports multi-turn dialogue items: $ref: '#/components/schemas/ChatMessage' example: - role: system content: You are a helpful assistant. - role: user content: Hello, please introduce yourself. temperature: type: number minimum: 0 maximum: 2 default: 1 description: >- Sampling temperature. Higher values (e.g., 0.8) make output more random, lower values (e.g., 0.2) make it more deterministic. max_tokens: type: integer minimum: 1 description: >- Maximum number of tokens to generate. Different models have different limits. top_p: type: number minimum: 0 maximum: 1 default: 1 description: >- Nucleus sampling parameter. It is generally recommended not to modify both temperature and top_p. 'n': type: integer minimum: 1 default: 1 description: Number of completions to generate for each message. stream: type: boolean default: false description: >- Whether to stream results. The Playground does not support streaming preview — use an SDK to test. stop: oneOf: - type: string - type: array items: type: string description: >- Stop sequence(s). Generation stops when this sequence is encountered. Up to 4. presence_penalty: type: number minimum: -2 maximum: 2 default: 0 description: >- Presence penalty. Positive values increase the likelihood of talking about new topics. frequency_penalty: type: number minimum: -2 maximum: 2 default: 0 description: >- Frequency penalty. Positive values decrease the likelihood of repeating the same text verbatim. user: type: string description: >- A unique identifier for the end user, used for monitoring and abuse detection. ChatCompletionResponse: type: object properties: id: type: string description: Unique identifier for the request example: chatcmpl-abc123 object: type: string enum: - chat.completion example: chat.completion created: type: integer description: Creation timestamp (Unix seconds) example: 1702855400 model: type: string description: The model actually used example: gpt-4o choices: type: array items: $ref: '#/components/schemas/ChatChoice' usage: $ref: '#/components/schemas/Usage' ErrorResponse: type: object properties: error: type: object properties: message: type: string description: Error description example: Invalid API key provided type: type: string description: Error type example: invalid_request_error param: type: string nullable: true description: Parameter that caused the error code: type: string description: Error code example: invalid_api_key ChatMessage: type: object required: - role - content properties: role: type: string enum: - system - user - assistant description: >- Message role: system (system prompt), user (user input), assistant (assistant reply) content: oneOf: - type: string - type: array items: type: object description: >- Message content. Supports plain text string or multimodal content array (image + text). ChatChoice: type: object properties: index: type: integer example: 0 message: $ref: '#/components/schemas/ChatMessage' finish_reason: type: string enum: - stop - length - content_filter - function_call - tool_calls description: >- Finish reason: stop (natural end), length (reached max_tokens), content_filter (triggered content filter) example: stop Usage: type: object description: Token usage statistics properties: prompt_tokens: type: integer description: Number of input tokens example: 25 completion_tokens: type: integer description: Number of output tokens example: 150 total_tokens: type: integer description: Total number of tokens example: 175 securitySchemes: bearerAuth: type: http scheme: bearer description: API Key obtained from the APIYI Console ````