Anthropic Messages

Endpoint

POST /anthropic/v1/messages

Fully compatible with the Anthropic Messages API.

SDK base URL

When using the Anthropic SDK, set the base URL to:

https://api.cheapestinference.com/anthropic

The SDK appends /v1/messages automatically.

Request body

Parameter	Type	Required	Description
model	string	Yes	Model ID (e.g. claude-sonnet-4-20250514)
max_tokens	integer	Yes	Maximum tokens to generate
messages	array	Yes	Array of message objects
stream	boolean	No	Enable SSE streaming
temperature	number	No	Sampling temperature (0–1)
system	string	No	System prompt

Example

cURL

curl https://api.cheapestinference.com/anthropic/v1/messages \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -H "anthropic-version: 2023-06-01" \
  -d '{
    "model": "claude-sonnet-4-20250514",
    "max_tokens": 1024,
    "messages": [
      {"role": "user", "content": "Hello!"}
    ]
  }'

Python

from anthropic import Anthropic

client = Anthropic(
    api_key="YOUR_API_KEY",
    base_url="https://api.cheapestinference.com/anthropic"
)

message = client.messages.create(
    model="claude-sonnet-4-20250514",
    max_tokens=1024,
    messages=[{"role": "user", "content": "Hello!"}]
)
print(message.content[0].text)

Node.js

import Anthropic from "@anthropic-ai/sdk";

const client = new Anthropic({
  apiKey: "YOUR_API_KEY",
  baseURL: "https://api.cheapestinference.com/anthropic",
});

const message = await client.messages.create({
  model: "claude-sonnet-4-20250514",
  max_tokens: 1024,
  messages: [{ role: "user", content: "Hello!" }],
});
console.log(message.content[0].text);

Response

{
  "id": "msg_abc123",
  "type": "message",
  "role": "assistant",
  "model": "claude-sonnet-4-20250514",
  "content": [
    {
      "type": "text",
      "text": "Hello! How can I help you today?"
    }
  ],
  "stop_reason": "end_turn",
  "usage": {
    "input_tokens": 10,
    "output_tokens": 12
  }
}

Non-Claude models

You can also use non-Claude models through the Anthropic endpoint. The API translates the format automatically:

message = client.messages.create(
    model="gpt-4o-mini",
    max_tokens=1024,
    messages=[{"role": "user", "content": "Hello!"}]
)