> ## Documentation Index > Fetch the complete documentation index at: https://docs.relace.ai/llms.txt > Use this file to discover all available pages before exploring further. # Chat Completions > Send an OpenAI-compatible chat completions request to a Relace-hosted model. OpenAI-compatible endpoint for open-weights models hosted on Relace infrastructure. You can also use this by pointing any OpenAI SDK at `https://models.relace.ai/v1` with your Relace API key. ## Models | Model | `model` ID | Context | Input | Output | Cached Input | | ---------------------- | ------------------------------------ | ------- | ------------- | ------------ | ------------- | | DeepSeek V4 Flash 0731 | `deepseek-ai/DeepSeek-V4-Flash-0731` | 1M | \$0.065 / M | \$0.18 / M | \$0.016 / M | | Kimi K3 | `moonshotai/kimi-k3` | 1M | \$3.00 / M | \$15.00 / M | \$0.30 / M | | GLM 5.3 Flash | `z-ai/glm-5.3-flash` | 1M | \$0.07125 / M | \$0.2375 / M | \$0.01425 / M | See the [Open Models guide](/docs/open-models/quickstart) for SDK examples and streaming. ## Prompt Caching Prompt caching is automatic. Cache hits are billed at the Cached Input rate and reported in `usage.prompt_tokens_details.cached_tokens`. To keep a multi-turn session on its cache, set `prompt_cache_key` to a stable value per session. See [Prompt Caching and Session Affinity](/docs/open-models/quickstart#prompt-caching-and-session-affinity). ## OpenAPI ````yaml POST /v1/chat/completions openapi: 3.0.1 info: title: Relace API description: API for accessing Relace code generation models. version: 1.0.0 license: name: MIT servers: - url: https://models.relace.ai description: Server for model API endpoints - url: https://api.relace.run description: Server for general infrastructure security: - bearerAuth: [] paths: /v1/chat/completions: post: description: >- Send an OpenAI-compatible chat completions request to a Relace-hosted model. requestBody: description: OpenAI-compatible chat completions request required: true content: application/json: schema: $ref: '#/components/schemas/ChatCompletionsRequest' example: model: deepseek-ai/DeepSeek-V4-Flash-0731 messages: - role: user content: Write a binary search in Python. stream: false responses: '200': description: Chat completion generated content: application/json: schema: $ref: '#/components/schemas/ChatCompletionsResponse' text/event-stream: schema: type: string description: >- Stream of chat completion chunks in the OpenAI streaming format. Token usage is reported in the final chunk. '400': description: Bad request content: application/json: schema: $ref: '#/components/schemas/OpenAIError' '401': description: Unauthorized content: application/json: schema: $ref: '#/components/schemas/OpenAIError' '402': description: Out of credits, or no payment method on the account content: application/json: schema: $ref: '#/components/schemas/OpenAIError' '404': description: Route not found content: application/json: schema: $ref: '#/components/schemas/OpenAIError' '429': description: Rate limit exceeded, or the model is at capacity headers: Retry-After: schema: type: string description: Seconds to wait before retrying content: application/json: schema: $ref: '#/components/schemas/OpenAIError' '500': description: Internal server error content: application/json: schema: $ref: '#/components/schemas/OpenAIError' '502': description: Model server error content: application/json: schema: $ref: '#/components/schemas/OpenAIError' '503': description: Model temporarily unavailable headers: Retry-After: schema: type: string description: Seconds to wait before retrying content: application/json: schema: $ref: '#/components/schemas/OpenAIError' '504': description: Request to the model timed out content: application/json: schema: $ref: '#/components/schemas/OpenAIError' servers: - url: https://models.relace.ai components: schemas: ChatCompletionsRequest: type: object required: - model - messages properties: model: type: string description: >- ID of the hosted model to use, e.g. `deepseek-ai/DeepSeek-V4-Flash-0731` or `moonshotai/kimi-k3`. messages: type: array items: type: object description: >- The conversation so far, as OpenAI-format message objects with `role` and `content`. stream: type: boolean description: >- If true, tokens are sent as server-sent events as they are generated. Token usage is always reported in the final chunk of the stream. max_tokens: type: integer description: >- Maximum number of tokens to generate. Reasoning tokens count toward this limit, so set a generous budget. temperature: type: number description: Sampling temperature. Higher values make output more random. top_p: type: number description: >- Nucleus sampling: only tokens within the top `top_p` probability mass are considered. top_k: type: integer description: Only the `top_k` most likely tokens are considered at each step. stop: type: array items: type: string description: Up to 4 sequences at which generation stops. frequency_penalty: type: number description: >- Penalizes tokens by how often they have appeared so far. Range -2 to 2. presence_penalty: type: number description: Penalizes tokens that have appeared at all so far. Range -2 to 2. repetition_penalty: type: number description: >- Multiplicative penalty on repeated tokens. Values above 1 discourage repetition. tools: type: array items: type: object description: OpenAI-format function tool definitions the model may call. tool_choice: description: 'Controls tool use: `none`, `auto`, `required`, or a specific tool.' response_format: type: object description: 'Set to `{"type": "json_object"}` for JSON mode. Kimi K3 only.' prompt_cache_key: type: string maxLength: 512 description: >- Cache affinity key. Requests with the same key are served by the same server, improving cache hit rates for multi-turn sessions. Use a stable value per conversation or session. Compatible with OpenAI's parameter of the same name. additionalProperties: true description: >- OpenAI-compatible request. Supported sampling parameters vary slightly by model. ChatCompletionsResponse: type: object properties: id: type: string description: Unique identifier for the completion object: type: string description: Always `chat.completion` created: type: integer description: Unix timestamp of when the completion was created model: type: string description: The model that served the request choices: type: array items: type: object properties: index: type: integer message: type: object description: >- The generated message, with `role` and `content` (and `tool_calls` when the model called tools) finish_reason: type: string description: Why generation stopped, e.g. `stop`, `length`, or `tool_calls` description: The generated completions usage: type: object properties: prompt_tokens: type: integer description: Number of tokens in the prompt completion_tokens: type: integer description: Number of tokens in the completion total_tokens: type: integer description: Total number of tokens used description: Token usage information for the request OpenAIError: type: object properties: error: type: object properties: message: type: string description: Error message example: >- Rate limit exceeded. Retry after the Retry-After interval, or contact support to raise your limits. type: type: string description: OpenAI error type enum: - invalid_request_error - authentication_error - insufficient_quota - rate_limit_error - api_error example: rate_limit_error param: type: string nullable: true description: Offending request parameter, when known example: null code: type: string nullable: true description: Always null on Relace-authored errors example: null securitySchemes: bearerAuth: type: http scheme: bearer description: Relace API key Authorization header using the Bearer scheme. ````