Anthropic

Route your Anthropic Claude requests through Metrion to track token usage, costs, and latency — with a one-line SDK change.

Use Metrion as a drop-in proxy for Anthropic’s API. Your requests pass through https://www.metrion.dev/api/proxy, Metrion logs the usage, and the response comes back unchanged.

Prerequisites

• A Metrion account with your sk-metrion-xxx token (find it on the Integrate page)
• An Anthropic API key saved in Metrion’s Integrate page

Setup

1. Install the Anthropic SDK
2. TypeScript

   npm install @anthropic-ai/sdk
   

   Python

   pip install anthropic
   
3. Configure the client
4. Replace the default Anthropic base URL with Metrion’s proxy and use your sk-metrion-xxx token as the API key. The SDK automatically appends /v1/messages to the baseURL.
5. TypeScript

   import Anthropic from '@anthropic-ai/sdk'
   
   const client = new Anthropic({
     apiKey: 'sk-metrion-xxx',       // your Metrion token
     baseURL: 'https://www.metrion.dev/api/proxy',
   })
   

   Python

   import anthropic
   
   client = anthropic.Anthropic(
       api_key="sk-metrion-xxx",     # your Metrion token
       base_url="https://www.metrion.dev/api/proxy",
   )
   
6. Send a request
7. TypeScript

   import Anthropic from '@anthropic-ai/sdk'
   
   const client = new Anthropic({
     apiKey: 'sk-metrion-xxx',
     baseURL: 'https://www.metrion.dev/api/proxy',
   })
   
   const message = await client.messages.create({
     model: 'claude-sonnet-4-6',
     max_tokens: 1024,
     messages: [{ role: 'user', content: 'Hello, world!' }],
   })
   
   console.log(message.content)
   

   Python

   import anthropic
   
   client = anthropic.Anthropic(
       api_key="sk-metrion-xxx",
       base_url="https://www.metrion.dev/api/proxy",
   )
   
   message = client.messages.create(
       model="claude-sonnet-4-6",
       max_tokens=1024,
       messages=[{"role": "user", "content": "Hello, world!"}],
   )
   
   print(message.content)
   

Direct HTTP

If you prefer to call the API without a SDK, POST directly to the messages endpoint:

curl https://www.metrion.dev/api/proxy/messages \
  -H 'x-api-key: sk-metrion-xxx' \
  -H 'anthropic-version: 2023-06-01' \
  -H 'content-type: application/json' \
  -d '{
    "model": "claude-sonnet-4-6",
    "max_tokens": 1024,
    "messages": [{"role": "user", "content": "Hello, world!"}]
  }'

Supported models

Model ID	Display name
claude-opus-4-6	Claude Opus 4
claude-sonnet-4-6	Claude Sonnet 4
claude-haiku-4-5-20251001	Claude Haiku 4

Metrion uses prefix matching, so versioned model IDs (e.g. claude-opus-4-6) are automatically mapped to the correct pricing tier.

Pass-through mode

If you want to manage your Anthropic key yourself instead of storing it in Metrion, use pass-through mode. Pass your Anthropic key in x-api-key and your Metrion token in x-metrion-token:

TypeScript

import Anthropic from '@anthropic-ai/sdk'

const client = new Anthropic({
  apiKey: process.env.ANTHROPIC_API_KEY,   // your Anthropic key directly
  baseURL: 'https://www.metrion.dev/api/proxy',
  defaultHeaders: {
    'x-metrion-token': 'sk-metrion-xxx',   // identifies your Metrion account
  },
})

import anthropic

client = anthropic.Anthropic(
    api_key=os.environ["ANTHROPIC_API_KEY"],
    base_url="https://www.metrion.dev/api/proxy",
    default_headers={"x-metrion-token": "sk-metrion-xxx"},
)

In pass-through mode, your Anthropic key is forwarded directly to Anthropic’s API and is never stored by Metrion.

Track requests by user or service

Add the optional x-metrion-user header to tag individual requests with a user ID, agent name, or service label. These labels appear in your Metrion logs and dashboards.

Use x-metrion-user to break down costs by team member, bot, or application — for example "x-metrion-user": "agent-summarizer" or "x-metrion-user": "user-42".

TypeScript

const client = new Anthropic({
  apiKey: 'sk-metrion-xxx',
  baseURL: 'https://www.metrion.dev/api/proxy',
  defaultHeaders: {
    'x-metrion-user': 'user-42',
  },
})

client = anthropic.Anthropic(
    api_key="sk-metrion-xxx",
    base_url="https://www.metrion.dev/api/proxy",
    default_headers={"x-metrion-user": "user-42"},
)