---
title: "Anthropic compatibility"
description: "Messages, token counting, and model listing at the Anthropic base URL."
---

> Documentation Index
> Fetch the complete documentation index at: https://docs.noket.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Anthropic compatibility

The Anthropic SDKs and Claude-style clients can call Noket through the Messages API. The routes are
served at two equivalent paths, so you can pick the base URL your client expects to append to.

| Base URL | Client appends | Use when |
| --- | --- | --- |
| `https://api.noket.dev/anthropic` | `/v1/messages` | The SDK takes a base URL and adds `/v1/...` itself, which the Anthropic SDK does. |
| `https://api.noket.dev` | `/v1/messages` | The client wants the provider's own path. |

| Method | Path | Purpose |
| --- | --- | --- |
| `POST` | `/v1/messages` | Messages. |
| `POST` | `/v1/messages/count_tokens` | Token counting. |
| `GET` | `/anthropic/v1/models` or `/anthropic/models` | Models your key can call. |

## Send a message

```bash
curl https://api.noket.dev/anthropic/v1/messages \
  -H "x-api-key: YOUR_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "alice/llama-3.1-8b",
    "max_tokens": 256,
    "messages": [{"role": "user", "content": "Hello"}]
  }'
```

```python
from anthropic import Anthropic

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

message = client.messages.create(
    model="alice/llama-3.1-8b",
    max_tokens=256,
    messages=[{"role": "user", "content": "Hello"}],
)
print(message.content[0].text)
```

A bearer token is also accepted where an Anthropic client sends `x-api-key`; if both headers are
present, `x-api-key` wins. See [Authentication](https://docs.noket.dev/api/authentication/).

## Request handling

Noket requires `model` and a non-empty `messages` array, and forwards the rest of the body to the
model unchanged: `system`, `max_tokens`, `temperature`, `tools`, `stream`, and the other Messages
fields behave as the provider implements them. The same routing and credential fields are stripped as
on the OpenAI routes, so a request cannot choose a provider or supply a key.

The response is the provider's Messages response. Noket replaces the internal model id with the public
id and removes internal metadata; `usage` keeps its token counts but not Noket's cost.

## Streaming

Send `stream: true`. Noket passes the Messages event stream through: `message_start`,
`content_block_delta`, `message_stop`, and the rest. A model configured without streaming support
returns `400` with `stream_not_supported`.

An error after the stream has started ends the stream; the HTTP status is already `200`, so read the
error event instead of the status code.

## Count tokens

```bash
curl https://api.noket.dev/anthropic/v1/messages/count_tokens \
  -H "x-api-key: YOUR_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "alice/llama-3.1-8b",
    "messages": [{"role": "user", "content": "Hello"}]
  }'
```

Token counting runs no generation and costs nothing against a budget. The reply is the provider's
`{"input_tokens": ...}` body.

## List models

```bash
curl https://api.noket.dev/anthropic/v1/models \
  -H "x-api-key: YOUR_API_KEY"
```

```json
{
  "data": [
    {
      "type": "model",
      "id": "alice/llama-3.1-8b",
      "display_name": "Llama 3.1 8B",
      "created_at": "2025-03-04T09:12:00.000Z"
    }
  ],
  "has_more": false,
  "first_id": "alice/llama-3.1-8b",
  "last_id": "alice/llama-3.1-8b"
}
```

The catalog fits in one page, so `has_more` is always `false`. `display_name` is the model's name in
the console — the name its owner gave it, not the provider's model name.

## Errors

Anthropic routes use the Anthropic error envelope:

```json
{
  "type": "error",
  "error": {
    "type": "rate_limit_error",
    "message": "Your traffic quota has been exceeded."
  }
}
```

See [Errors and limits](https://docs.noket.dev/api/errors/) for the statuses and messages both dialects can return.

## Next

- [OpenAI compatibility](https://docs.noket.dev/api/openai/)
- [Errors and limits](https://docs.noket.dev/api/errors/)
- [Examples](https://docs.noket.dev/api/examples/)

Source: https://docs.noket.dev/api/anthropic/index.mdx