--- title: Chat Completions product: vercel url: /docs/ai-gateway/sdks-and-apis/openai-chat-completions/chat-completions canonical_url: "https://vercel.com/docs/ai-gateway/sdks-and-apis/openai-chat-completions/chat-completions" last_updated: 2026-07-28 type: reference prerequisites: - /docs/ai-gateway/sdks-and-apis/openai-chat-completions - /docs/ai-gateway/sdks-and-apis related: - /docs/ai-gateway/sdks-and-apis/openai-chat-completions/streaming - /docs/ai-gateway/sdks-and-apis/openai-chat-completions/images - /docs/ai-gateway/sdks-and-apis/openai-chat-completions/advanced - /docs/ai-gateway/sdks-and-apis/openai-chat-completions/structured-outputs summary: Create chat completions using the Chat Completions API with support for streaming, image attachments, and PDF documents. install_vercel_plugin: npx plugins add vercel/vercel-plugin --- # Chat Completions Create chat completions using various AI models available through the AI Gateway. ## Related pages > **For AI agents:** Follow these links to understand how this page connects to the rest of the Vercel ecosystem. For the full cross-link map (inbound, outbound, prerequisites, and semantic neighbors), see the .graph.md link below. - [useCompletion](https://ai-sdk.dev/docs/reference/ai-sdk-ui/use-completion?from=related) - [Create Chat](https://v0.app/docs/api/v2/reference/chats/create-chat?from=related) — Creates a new chat from a prompt. The request blocks until the model response is complete and returns the chat. - [Image Generation](https://vercel.com/docs/ai-gateway/sdks-and-apis/openai-chat-completions/image-generation?from=related) — Generate images using AI models that support multimodal output through the Chat Completions API. - [Python](https://vercel.com/docs/ai-gateway/sdks-and-apis/python?from=related) — Use the AI Gateway with Python through OpenAI or Anthropic SDKs with full streaming, tool calling, and async support. - [REST API](https://vercel.com/docs/ai-gateway/sdks-and-apis/openai-chat-completions/rest-api?from=related) — Use the AI Gateway API directly without client libraries using curl and fetch. - [OpenAI Responses API](https://vercel.com/docs/ai-gateway/sdks-and-apis/responses?from=related) — Use the OpenAI Responses API with AI Gateway to generate text, call tools, stream tokens, and more across any supported - [Tool Calling](https://vercel.com/docs/ai-gateway/sdks-and-apis/openai-chat-completions/tool-calling?from=related) — Use function calling with the Chat Completions API to enable models to call tools and functions through AI Gateway. Full cross-link map for this page: [/docs/ai-gateway/sdks-and-apis/openai-chat-completions/chat-completions.graph.md](/docs/ai-gateway/sdks-and-apis/openai-chat-completions/chat-completions.graph.md) Endpoint ``` POST /chat/completions ``` ### Basic chat completion Create a non-streaming chat completion. Example request #### cURL ```bash filename="chat-completion.sh" curl -X POST "https://ai-gateway.vercel.sh/v1/chat/completions" \ -H "Authorization: Bearer $AI_GATEWAY_API_KEY" \ -H "Content-Type: application/json" \ -d '{ "model": "anthropic/claude-opus-5", "messages": [ { "role": "user", "content": "Write a one-sentence bedtime story about a unicorn." } ], "stream": false }' ``` #### TypeScript ```typescript filename="chat-completion.ts" import OpenAI from 'openai'; const apiKey = process.env.AI_GATEWAY_API_KEY || process.env.VERCEL_OIDC_TOKEN; const openai = new OpenAI({ apiKey, baseURL: 'https://ai-gateway.vercel.sh/v1', }); const completion = await openai.chat.completions.create({ model: 'anthropic/claude-opus-5', messages: [ { role: 'user', content: 'Write a one-sentence bedtime story about a unicorn.', }, ], stream: false, }); console.log('Assistant:', completion.choices[0].message.content); console.log('Tokens used:', completion.usage); ``` #### Python ```python filename="chat-completion.py" import os from openai import OpenAI api_key = os.getenv('AI_GATEWAY_API_KEY') or os.getenv('VERCEL_OIDC_TOKEN') client = OpenAI( api_key=api_key, base_url='https://ai-gateway.vercel.sh/v1' ) completion = client.chat.completions.create( model='anthropic/claude-opus-5', messages=[ { 'role': 'user', 'content': 'Write a one-sentence bedtime story about a unicorn.' } ], stream=False, ) print('Assistant:', completion.choices[0].message.content) print('Tokens used:', completion.usage) ``` Response format ```json { "id": "chatcmpl-123", "object": "chat.completion", "created": 1677652288, "model": "anthropic/claude-opus-5", "choices": [ { "index": 0, "message": { "role": "assistant", "content": "Once upon a time, a gentle unicorn with a shimmering silver mane danced through moonlit clouds, sprinkling stardust dreams upon sleeping children below." }, "finish_reason": "stop" } ], "usage": { "prompt_tokens": 15, "completion_tokens": 28, "total_tokens": 43 } } ``` ### Streaming chat completion Set `stream: true` to receive tokens as they are generated. See [Streaming](/docs/ai-gateway/sdks-and-apis/openai-chat-completions/streaming) for the full example and the server-sent event format. ### File attachments Send images and PDF documents by using an array of content parts in place of a plain string. See [File attachments](/docs/ai-gateway/sdks-and-apis/openai-chat-completions/images) for the full examples and supported types. ### Parameters The chat completions endpoint supports the following parameters: #### Required parameters - `model` (string): The model to use for the completion (e.g., `anthropic/claude-opus-5`) - `messages` (array): Array of message objects with `role` and `content` fields #### Optional parameters - `stream` (boolean): Whether to stream the response. Defaults to `false` - `temperature` (number): Controls randomness in the output. Range: 0-2 - `max_tokens` (integer): Maximum number of tokens to generate - `top_p` (number): Nucleus sampling parameter. Range: 0-1 - `frequency_penalty` (number): Penalty for frequent tokens. Range: -2 to 2 - `presence_penalty` (number): Penalty for present tokens. Range: -2 to 2 - `stop` (string or array): Stop sequences for the generation - `tools` (array): Array of tool definitions for function calling - `tool_choice` (string or object): Controls which tools are called (`auto`, `none`, or specific function) - `providerOptions` (object): [Provider routing and configuration options](/docs/ai-gateway/sdks-and-apis/openai-chat-completions/advanced#provider-options) - `provider` (object): Shorthand for provider routing. Supports `sort` (`'cost'`, `'ttft'`, `'tps'`). Equivalent to setting `providerOptions.gateway.sort`. See [Provider sorting](/docs/ai-gateway/sdks-and-apis/openai-chat-completions/advanced#provider-sorting) - `response_format` (object): Controls the format of the model's response - For OpenAI standard format: `{ type: "json_schema", json_schema: { name, schema, strict?, description? } }` - For legacy format: `{ type: "json", schema?, name?, description? }` - For plain text: `{ type: "text" }` - See [Structured outputs](/docs/ai-gateway/sdks-and-apis/openai-chat-completions/structured-outputs) for detailed examples ### Message format Messages support different content types: #### Text messages ```json { "role": "user", "content": "Hello, how are you?" } ``` #### Multimodal messages ```json { "role": "user", "content": [ { "type": "text", "text": "What's in this image?" }, { "type": "image_url", "image_url": { "url": "data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQABAAD..." } } ] } ``` #### File messages ```json { "role": "user", "content": [ { "type": "text", "text": "Summarize this document" }, { "type": "file", "file": { "data": "JVBERi0xLjQKJcfsj6IKNSAwIG9iago8PAovVHlwZSAvUGFnZQo...", "media_type": "application/pdf", "filename": "document.pdf" } } ] } ``` --- [View full sitemap](/docs/sitemap)