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

# LLM Proxy

> Reverse proxy for OpenAI and Anthropic with automatic token tracking

Base URL: `https://api.nozle.app/api/v1`

Reverse proxy routes that forward LLM requests to OpenAI or Anthropic and automatically track token usage. The proxy reads the response to extract `{ model, input_tokens, output_tokens, latency_ms }` and fires an internal `nozle.track()` event — no SDK wrapper needed on your side.

<Warning>
  LLM proxy routes use `X-Nozle-Key` for Nozle authentication, **not** the `Authorization` header. The `Authorization` header is reserved for the customer's own LLM provider API key, which the proxy forwards untouched to the provider.
</Warning>

***

## /api/v1/proxy/openai/v1/\*

Proxies all requests to `https://api.openai.com/v1/*`. Any OpenAI-compatible endpoint works (chat completions, embeddings, etc.).

**Auth:** `X-Nozle-Key` header (`sk_` only)

**Required headers:**

| Header             | Description                                 |
| ------------------ | ------------------------------------------- |
| `X-Nozle-Key`      | Your Nozle secret key (`sk_live_...`)       |
| `X-Nozle-Customer` | External customer ID to bill for this usage |
| `Authorization`    | Customer's OpenAI API key (`Bearer sk-...`) |

```bash title="cURL" theme={null}
curl -X POST https://api.nozle.app/api/v1/proxy/openai/v1/chat/completions \
  -H "X-Nozle-Key: sk_live_your_nozle_key" \
  -H "X-Nozle-Customer: cust_123" \
  -H "Authorization: Bearer sk-customer-openai-key" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-4o",
    "messages": [{"role": "user", "content": "Hello"}]
  }'
```

***

## /api/v1/proxy/anthropic/v1/\*

Proxies all requests to `https://api.anthropic.com/v1/*`.

**Auth:** `X-Nozle-Key` header (`sk_` only)

**Required headers:**

| Header             | Description                                 |
| ------------------ | ------------------------------------------- |
| `X-Nozle-Key`      | Your Nozle secret key (`sk_live_...`)       |
| `X-Nozle-Customer` | External customer ID to bill for this usage |
| `Authorization`    | Customer's Anthropic API key                |

```bash title="cURL" theme={null}
curl -X POST https://api.nozle.app/api/v1/proxy/anthropic/v1/messages \
  -H "X-Nozle-Key: sk_live_your_nozle_key" \
  -H "X-Nozle-Customer: cust_123" \
  -H "x-api-key: customer-anthropic-key" \
  -H "anthropic-version: 2023-06-01" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-sonnet-4-20250514",
    "max_tokens": 1024,
    "messages": [{"role": "user", "content": "Hello"}]
  }'
```

<Info>
  The proxy returns the provider's response unchanged. Your customer's API key is forwarded but never stored. Token usage is extracted from the response and tracked automatically as a billing event on the `llm_tokens` metric.
</Info>