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

# Migrate from OpenAI SDK

> Switch from OpenAI to Routor in two minutes with three line changes.

# Migrate from OpenAI SDK

Switching from OpenAI to Routor takes two minutes and three line changes. Your existing SDK, your existing patterns, your existing code. Nothing else moves.

***

## Before and After

### Node.js / TypeScript

**Before:**

```typescript theme={null}
import OpenAI from "openai";

const client = new OpenAI({
  apiKey: process.env.OPENAI_API_KEY,
});

const response = await client.chat.completions.create({
  model:    "gpt-4o",
  messages: [{ role: "user", content: prompt }],
});
```

**After:**

```typescript theme={null}
import OpenAI from "openai";

const client = new OpenAI({
  apiKey:  process.env.ROUTOR_API_KEY,    // change 1
  baseURL: "https://api.routor.ai/v1",   // change 2
});

const response = await client.chat.completions.create({
  model:    "auto",                        // change 3
  messages: [{ role: "user", content: prompt }],
});
```

Three changes. Everything else stays the same.

***

### Python

**Before:**

```python theme={null}
from openai import OpenAI

client = OpenAI(api_key=os.environ["OPENAI_API_KEY"])

response = client.chat.completions.create(
    model="gpt-4o",
    messages=[{"role": "user", "content": prompt}]
)
```

**After:**

```python theme={null}
from openai import OpenAI

client = OpenAI(
    api_key=os.environ["ROUTOR_API_KEY"],
    base_url="https://api.routor.ai/v1",
)

response = client.chat.completions.create(
    model="auto",
    messages=[{"role": "user", "content": prompt}]
)
```

***

## Environment Variable

Add your Routor key to `.env`:

```bash theme={null}
ROUTOR_API_KEY=sk-routor-YOUR_KEY_HERE
```

Keep your `OPENAI_API_KEY` if you use OpenAI directly anywhere else. They are completely separate.

***

## What Changes in Practice

|                     | OpenAI direct         | With Routor                   |
| ------------------- | --------------------- | ----------------------------- |
| Model used          | Always GPT-5.5        | Right model for each prompt   |
| Cost                | Fixed GPT-5.5 pricing | 25 to 70% lower on average    |
| Failover            | None                  | Automatic across 13 providers |
| `model` in response | `"gpt-4o"`            | Actual model used             |
| Response format     | OpenAI format         | Identical OpenAI format       |

***

## Gradual Rollout

You do not have to switch everything at once. Routor runs alongside direct OpenAI calls. They are independent. Keep critical features on a direct GPT-5.5 call while you test Routor on lower-stakes requests:

```typescript theme={null}
const routorClient = new OpenAI({
  apiKey:  process.env.ROUTOR_API_KEY,
  baseURL: "https://api.routor.ai/v1",
});

// Regular requests go through Routor
const regularResponse = await routorClient.chat.completions.create({
  model:    "auto",
  messages: [...],
});

// High-stakes requests: force COMPLEX tier minimum
const criticalResponse = await routorClient.chat.completions.create({
  model:             "auto",
  routor_tier_floor: "COMPLEX",
  messages: [...],
});
```

***

## Verifying the Switch Worked

Check the `model` field in the response body. It will show the actual model used instead of `"auto"`:

```typescript theme={null}
console.log(response.model);
// "kimi-k2.6" — the provider's bare model id

// Non-streaming responses also include a routor object with the full decision:
console.log((response as any).routor);
// { model: "moonshot/kimi-k2.6", tier: "LIGHT", profile: "auto", savingsPct: 83.2, ... }
```

Or check the **Logs** page in your dashboard to see routing decisions in real time.

<Note>TypeScript users: extra fields like `routor_tier_floor` are accepted by the API and passed through by the SDK at runtime, but the SDK's types don't know them — add `// @ts-expect-error` above the line or cast the params object.</Note>