> ## Documentation Index > Fetch the complete documentation index at: https://runcrate.ai/docs/llms.txt > Use this file to discover all available pages before exploring further. # Chat / LLM completion > OpenAI-compatible chat completion endpoint. Drop-in replacement for `OpenAI(base_url='https://api.runcrate.ai/v1')`. ## OpenAPI ````yaml /api-reference/openapi.json post /chat/completions openapi: 3.1.0 info: title: Runcrate API version: 1.0.0 summary: OpenAI-compatible inference API + GPU infrastructure API. description: >- Runcrate exposes two API surfaces. The inference API at `https://api.runcrate.ai/v1` is OpenAI-compatible — it accepts the standard OpenAI SDK with the base URL changed. The infrastructure API at `https://runcrate.ai/api/v1` manages GPU instances, persistent volumes, environments, SSH keys, templates, and billing. Both share a single `rc_live_*` API key. Pricing is per-token, per-image, per-second, or per-minute on the inference API (varies by model; see https://www.runcrate.ai/api/models/catalog for live rates) and per-second on GPU rentals (see https://www.runcrate.ai/pricing for hourly rates per GPU class). All infrastructure API responses are wrapped in `{ "data": ... }`. List responses also include a `meta` object with pagination cursors. Error responses use `{ "error": { "code": "...", "message": "..." } }`. termsOfService: https://www.runcrate.ai/terms contact: name: Runcrate url: https://www.runcrate.ai/contact license: name: Proprietary url: https://www.runcrate.ai/terms servers: - url: https://api.runcrate.ai/v1 description: Inference API (OpenAI-compatible) - url: https://runcrate.ai/api/v1 description: >- Infrastructure API (instances, storage, environments, ssh-keys, templates, billing) security: - ApiKeyAuth: [] tags: - name: Chat description: OpenAI-compatible chat completions. - name: Images description: Text-to-image generation. - name: Videos description: Async text-to-video and image-to-video generation. - name: Audio description: Text-to-speech and speech-to-text. - name: Embeddings description: Vector embeddings for RAG and search. - name: Models description: Model catalog discovery. - name: Instances description: GPU instance lifecycle. - name: Storage description: Persistent volume management. - name: Environments description: Resource isolation containers within a workspace. - name: SSH Keys description: SSH key management for instance access. - name: Templates description: Pre-built instance images and configurations. - name: Billing description: Credit balance, transactions, usage metrics. paths: /chat/completions: post: tags: - Chat summary: Chat / LLM completion description: >- OpenAI-compatible chat completion endpoint. Drop-in replacement for `OpenAI(base_url='https://api.runcrate.ai/v1')`. operationId: createChatCompletion requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/ChatCompletionRequest' responses: '200': description: Completion (or SSE stream when stream=true). content: application/json: schema: $ref: '#/components/schemas/ChatCompletionResponse' text/event-stream: schema: type: string description: Server-sent event stream of OpenAI-compatible chunks. '401': $ref: '#/components/responses/Unauthorized' '402': $ref: '#/components/responses/PaymentRequired' '429': $ref: '#/components/responses/RateLimited' components: schemas: ChatCompletionRequest: type: object required: - model - messages properties: model: type: string description: Model id from the catalog (e.g. `deepseek/deepseek-v3.2`). messages: type: array items: $ref: '#/components/schemas/ChatMessage' max_tokens: type: integer minimum: 1 temperature: type: number minimum: 0 maximum: 2 top_p: type: number minimum: 0 maximum: 1 stop: oneOf: - type: string - type: array items: type: string frequency_penalty: type: number minimum: -2 maximum: 2 presence_penalty: type: number minimum: -2 maximum: 2 stream: type: boolean default: false tools: type: array items: type: object tool_choice: oneOf: - type: string - type: object response_format: type: object ChatCompletionResponse: type: object properties: id: type: string object: type: string enum: - chat.completion created: type: integer model: type: string choices: type: array items: type: object properties: index: type: integer message: $ref: '#/components/schemas/ChatMessage' finish_reason: type: string enum: - stop - length - tool_calls - content_filter usage: type: object properties: prompt_tokens: type: integer completion_tokens: type: integer total_tokens: type: integer ChatMessage: type: object required: - role - content properties: role: type: string enum: - system - user - assistant - tool name: type: string content: oneOf: - type: string - type: array items: type: object properties: type: type: string enum: - text - image_url text: type: string image_url: type: object properties: url: type: string format: uri Error: type: object required: - error properties: error: type: object required: - code - message properties: code: type: string description: >- Machine-readable error code (e.g. `validation_error`, `unauthorized`, `not_found`, `insufficient_credits`, `rate_limited`, `internal_error`). message: type: string description: Human-readable error message. details: type: object additionalProperties: true description: Optional structured error context. responses: Unauthorized: description: Missing or invalid API key. content: application/json: schema: $ref: '#/components/schemas/Error' PaymentRequired: description: Insufficient credits. content: application/json: schema: $ref: '#/components/schemas/Error' RateLimited: description: Rate limited. Retry with exponential backoff. content: application/json: schema: $ref: '#/components/schemas/Error' securitySchemes: ApiKeyAuth: type: http scheme: bearer description: >- Use a Runcrate API key with the `rc_live_*` prefix as the bearer token. Create one at https://www.runcrate.ai/dashboard/api-keys. ````