Proxy Anthropic Requests

Anthropic provides an OpenAI-compatible API that allows you to access Claude models using the familiar OpenAI API format.

This guide shows how to integrate APISIX with Anthropic using the ai-proxy plugin. With provider set to anthropic, you do not need to set a custom endpoint.

Prerequisite(s)

• Install Docker.
• Install cURL to send requests to the services for validation.
• Follow the Getting Started Tutorial to start a new APISIX instance in Docker or on Kubernetes.

Obtain an Anthropic API Key

Create an account and API key by following the Anthropic API Documentation. Optionally save the key to an environment variable:

export ANTHROPIC_API_KEY=sk-ant-xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx  # replace with your API key

Create a Route to Anthropic

Create a route with the ai-proxy plugin as such:

Admin API

curl "http://127.0.0.1:9180/apisix/admin/routes" -X PUT -d '{
  "id": "anthropic-chat",
  "uri": "/anything",
  "plugins": {
    "ai-proxy": {
      "provider": "anthropic",
      "auth": {
        "header": {
          "Authorization": "Bearer '"$ANTHROPIC_API_KEY"'"
        }
      },
      "options": {
        "model": "claude-sonnet-4-5"
      }
    }
  }
}'

❶ Set the provider to anthropic.

❷ Attach the Anthropic API key using the Authorization header.

❸ Set a model supported by Anthropic, for example claude-sonnet-4-5.

ADC

adc.yaml

services:
  - name: Anthropic Service
    routes:
      - uris:
          - /anything
        name: anthropic-chat
        plugins:
          ai-proxy:
            provider: anthropic
            auth:
              header:
                Authorization: "Bearer sk-ant-xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
            options:
              model: claude-sonnet-4-5

❶ Set the provider to anthropic.

❷ Attach the Anthropic API key using the Authorization header.

❸ Set a model supported by Anthropic, for example claude-sonnet-4-5.

Synchronize the configuration to APISIX:

adc sync -f adc.yaml

Verify

Send a request with the following prompts to the route:

curl "http://127.0.0.1:9080/anything" -X POST \
  -H "Content-Type: application/json" \
  -d '{"messages": [{"role": "user", "content": "Hello"}]}'

You should receive a response similar to the following:

{
  "request": {
    "messages": [
      {
        "role": "user",
        "content": "Hello"
      }
    ]
  },
  "response": {
    "id": "msg_01HUQ8fAR1XvJ9PodefrZixW",
    "object": "chat.completion",
    "created": 1770029318,
    "model": "claude-sonnet-4-5-20250929",
    "choices": [
      {
        "index": 0,
        "finish_reason": "stop",
        "message": {
          "role": "assistant",
          "content": "Hello! How can I help you today?"
        }
      }
    ],
    "usage": {
      "prompt_tokens": 8,
      "completion_tokens": 12,
      "total_tokens": 20
    }
  }
}

Next Steps

You have learned how to integrate APISIX with Anthropic. See the Anthropic API Documentation and Models pages for more details.

If you would like to stream responses, enable streaming in your request and use the proxy-buffering plugin to disable NGINX proxy_buffering to avoid server-sent events (SSE) being buffered.