Anthropic Compatibility

Inworld Router is available through Anthropic-compatible API endpoints, so you can use the Anthropic SDK and tools like Claude Code, while benefiting from Inworld Router's multi-provider routing, failover, and cost optimization.

Endpoint

The Anthropic-compatible Messages API is available at:

https://api.inworld.ai/v1/messages

When using the Anthropic SDK, set the base URL to https://api.inworld.ai. The SDK automatically appends /v1/messages.

Authentication

Use your Inworld API Key with the Authorization: Bearer header:

Authorization: Bearer <your-api-key>

When using the Anthropic SDK, pass your key via the auth_token parameter (not api_key), which sends it as Authorization: Bearer:

client = anthropic.Anthropic(
    base_url="https://api.inworld.ai",
    auth_token="YOUR_INWORLD_API_KEY",
)

Anthropic SDK

Below is an example request using Anthropic's SDK

import anthropic

client = anthropic.Anthropic(
    base_url="https://api.inworld.ai",
    auth_token="YOUR_INWORLD_API_KEY",  # Sends as Authorization: Bearer
)

message = client.messages.create(
    model="inworld/<router-id>",
    max_tokens=1024,
    messages=[
        {"role": "user", "content": "Explain how neural networks learn."}
    ]
)

print(message.content[0].text)

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

const client = new Anthropic({
  baseURL: 'https://api.inworld.ai',
  authToken: 'YOUR_INWORLD_API_KEY',  // Sends as Authorization: Bearer
});

const message = await client.messages.create({
  model: 'inworld/<router-id>',
  max_tokens: 1024,
  messages: [
    { role: 'user', content: 'Explain how neural networks learn.' }
  ],
});

console.log(message.content[0].text);

Response

The response follows the Anthropic Messages API format:

{
  "content": [
    {"text": "Neural networks learn through...", "type": "text"}
  ],
  "id": "msg-...",
  "model": "anthropic/claude-opus-4-6",
  "role": "assistant",
  "stop_reason": "end_turn",
  "type": "message",
  "usage": {
    "input_tokens": 12,
    "output_tokens": 150
  },
  "metadata": {
    "attempts": [
      {"model": "anthropic/claude-opus-4-6", "success": true, "time_to_first_token_ms": 1152}
    ],
    "generation_id": "019b...",
    "reasoning": "Using specified model: 'anthropic/claude-opus-4-6' - success"
  }
}

Next Steps

• Claude Code Integration to use Inworld Router as your Claude Code backend.
• Migrating from Anthropic for a step-by-step migration guide.