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"
  }
}

Inworld Router adds a metadata field to the response containing routing information — which model was selected, attempt history, and timing. This field is not part of the standard Anthropic response format, but it does not break Anthropic SDK parsing.

Next Steps

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

Getting Started

Core Concepts

Migration

Resources

Endpoint

Authentication

Anthropic SDK

Response

Next Steps

​Endpoint

​Authentication

​Anthropic SDK

​Response

​Next Steps

Endpoint

Authentication

Anthropic SDK

Response

Next Steps