Messages Format

Create a message response using the official Anthropic Claude Messages API format.

This endpoint only supports Claude models. Do not use OpenAI, DeepSeek, or other non-Claude models on this endpoint.

Try It

POST/v1/messageshttps://api-platform.ope.ai

Authentication

Use the platform API key.

• Header: Authorization: Bearer <api-key>
• Example: Authorization: Bearer sk-xxxxxx

You may pass the official Claude anthropic-version header, for example 2023-06-01.

Request Body (application/json)

Field	Type	Required	Description
model	string	Yes	Claude model ID
max_tokens	integer	Yes	Maximum tokens to generate
messages	array	Yes	Conversation message list
system	string | array	No	System prompt
stop_sequences	string[]	No	Custom stop sequences
stream	boolean	No	Whether to use SSE streaming
temperature	number	No	Sampling temperature
top_p	number	No	Nucleus sampling parameter
top_k	integer	No	Top-k sampling parameter
tools	array	No	Official Claude tool definition array
tool_choice	object	No	Tool selection strategy
thinking	object	No	Extended thinking configuration
metadata	object	No	Metadata

messages

Field	Type	Required	Description
role	string	Yes	user or assistant
content	string | array	Yes	Text content or an official Claude content block array

Request Examples

cURL

curl -X POST "https://api-platform.ope.ai/v1/messages" \
  -H "Authorization: Bearer $OPEAI_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-sonnet-4-5",
    "max_tokens": 1024,
    "messages": [
      {
        "role": "user",
        "content": "Hello, Claude"
      }
    ]
  }'

JavaScript

const res = await fetch("https://api-platform.ope.ai/v1/messages", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.OPEAI_API_KEY}`,
    "anthropic-version": "2023-06-01",
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    model: "claude-sonnet-4-5",
    max_tokens: 1024,
    messages: [{role: "user", content: "Hello, Claude"}],
  }),
});

console.log(await res.json());

Python

import os
import requests

resp = requests.post(
    "https://api-platform.ope.ai/v1/messages",
    headers={
        "Authorization": f"Bearer {os.environ['OPEAI_API_KEY']}",
        "anthropic-version": "2023-06-01",
    },
    json={
        "model": "claude-sonnet-4-5",
        "max_tokens": 1024,
        "messages": [{"role": "user", "content": "Hello, Claude"}],
    },
    timeout=60,
)

print(resp.json())

Response Example

{
  "id": "msg_01XFDUDYJgAACzvnptvVoYEL",
  "type": "message",
  "role": "assistant",
  "content": [
    {
      "type": "text",
      "text": "Hello!"
    }
  ],
  "model": "claude-sonnet-4-5",
  "stop_reason": "end_turn",
  "stop_sequence": null,
  "usage": {
    "input_tokens": 12,
    "output_tokens": 6
  }
}

Official reference: Claude Messages API