> ## Documentation Index > Fetch the complete documentation index at: https://docs.fanifyai.com/llms.txt > Use this file to discover all available pages before exploring further. # Chat Completion > Creates a synchronous chat completion from an OpenAI-compatible request. Provider failures preserve an upstream 4xx status when applicable and use the provider_error code; upstream 5xx failures return 503. ## OpenAPI ````yaml /hub/openapi/hub.json post /api/v1/hub/chat/completions openapi: 3.0.1 info: title: Fanify Hub API description: Generate media and text with Fanify credits. All prices use EUR. version: v1 servers: - url: https://fanifyai.com security: [] paths: /api/v1/hub/chat/completions: post: tags: - Chat summary: Chat Completion description: >- Creates a synchronous chat completion from an OpenAI-compatible request. Provider failures preserve an upstream 4xx status when applicable and use the provider_error code; upstream 5xx failures return 503. parameters: - name: Idempotency-Key in: header description: Optional idempotency key, from 1 to 255 characters. schema: type: string requestBody: description: >- OpenAI-compatible chat completion request. Additional top-level fields are forwarded. The stream field must be omitted or false; n is not supported and must be omitted. content: application/json: schema: required: - model - messages type: object properties: model: type: string messages: type: array items: type: object example: model: deepseek-v4-flash-0731 messages: - role: user content: Hello required: true responses: '200': description: OpenAI-compatible chat completion. headers: X-Fanify-Generation-Id: description: Hub generation identifier. schema: type: string X-Fanify-Billed-Cost: description: Billed cost in EUR, using invariant decimal notation. schema: type: string content: application/json: schema: type: object example: id: 0192f3a4-8c1e-7b2a-9f10-2b6d4e0c9a11 object: chat.completion created: 1757239231 model: deepseek-v4-flash-0731 choices: - index: 0 message: role: assistant content: Hello! finish_reason: stop usage: prompt_tokens: 10 completion_tokens: 120 total_tokens: 130 cost: 0.000041 '400': description: OpenAI-compatible error. content: application/json: schema: required: - error type: object properties: error: required: - message - code - type - metadata type: object properties: message: type: string code: enum: - invalid_input - provider_error type: string type: type: string metadata: required: - provider_name type: object properties: provider_name: enum: - FanifyHub type: string example: error: message: The request input is invalid. code: invalid_input type: invalid_request_error metadata: provider_name: FanifyHub '401': description: Unauthorized content: application/problem+json: schema: required: - type - title - status - code type: object properties: type: type: string format: uri title: type: string status: type: integer format: int32 detail: type: string nullable: true instance: type: string code: enum: - unauthorized type: string errors: type: object additionalProperties: type: array items: type: string unrepresentable: type: array items: type: string example: type: https://fanifyai.com/docs/hub/errors#unauthorized title: Unauthorized status: 401 code: unauthorized '402': description: OpenAI-compatible error. content: application/json: schema: required: - error type: object properties: error: required: - message - code - type - metadata type: object properties: message: type: string code: enum: - insufficient_credits type: string type: type: string metadata: required: - provider_name type: object properties: provider_name: enum: - FanifyHub type: string example: error: message: Your available balance does not cover this generation. code: insufficient_credits type: invalid_request_error metadata: provider_name: FanifyHub '404': description: OpenAI-compatible error. content: application/json: schema: required: - error type: object properties: error: required: - message - code - type - metadata type: object properties: message: type: string code: enum: - model_not_found type: string type: type: string metadata: required: - provider_name type: object properties: provider_name: enum: - FanifyHub type: string example: error: message: The requested model was not found. code: model_not_found type: invalid_request_error metadata: provider_name: FanifyHub '410': description: OpenAI-compatible error. content: application/json: schema: required: - error type: object properties: error: required: - message - code - type - metadata type: object properties: message: type: string code: enum: - file_expired type: string type: type: string metadata: required: - provider_name type: object properties: provider_name: enum: - FanifyHub type: string example: error: message: The requested file has expired or is unavailable. code: file_expired type: invalid_request_error metadata: provider_name: FanifyHub '422': description: OpenAI-compatible error. content: application/json: schema: required: - error type: object properties: error: required: - message - code - type - metadata type: object properties: message: type: string code: enum: - idempotency_conflict type: string type: type: string metadata: required: - provider_name type: object properties: provider_name: enum: - FanifyHub type: string example: error: message: >- This idempotency key was already used with a different request. code: idempotency_conflict type: invalid_request_error metadata: provider_name: FanifyHub '429': description: OpenAI-compatible error. headers: Retry-After: description: Seconds before retrying. schema: type: string content: application/json: schema: required: - error type: object properties: error: required: - message - code - type - metadata type: object properties: message: type: string code: enum: - rate_limited type: string type: type: string metadata: required: - provider_name type: object properties: provider_name: enum: - FanifyHub type: string example: error: message: Rate limit reached, retry later. code: rate_limited type: invalid_request_error metadata: provider_name: FanifyHub '503': description: OpenAI-compatible error. headers: Retry-After: description: Always 5 seconds for an in-progress replay. schema: type: string content: application/json: schema: required: - error type: object properties: error: required: - message - code - type - metadata type: object properties: message: type: string code: enum: - generation_in_progress - provider_error type: string type: type: string metadata: required: - provider_name type: object properties: provider_name: enum: - FanifyHub type: string example: error: message: A generation with this idempotency key is still in progress. code: generation_in_progress type: invalid_request_error metadata: provider_name: FanifyHub security: - Bearer: [] components: securitySchemes: Bearer: type: http description: Fanify API key. scheme: bearer bearerFormat: fanify_sk_... ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.