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

# API Router Overview

> Overview of the Alter API Router service and OpenAI-compatible endpoint

The Alter API Router is an OpenAI-compatible API gateway that provides unified access to 92+ AI models from 10+ providers through a single endpoint.

## What is the API Router?

The API Router is a centralized service that eliminates the need to manage multiple API keys and billing accounts across different AI providers. Instead of maintaining separate accounts with OpenAI, Anthropic, Google, and others, you can use Alter as your single entry point for all AI model access.

### Key Benefits

* **Single API key** for all providers
* **Centralized billing** through your Alter account
* **92+ models** from 10+ providers
* **OpenAI-compatible endpoint** works with existing tools and SDKs
* **Easy model switching** without code changes

## Quick Start

### 1. Generate an API Key

1. Open **Settings** (**⌘ ,**)
2. Go to the **Router** tab
3. Under "Alter API Keys", click **Add New Key**
4. Copy your key (starts with `sk-`)

### 2. Get the Endpoint

```
https://alterhq.com/api
```

For most tools, use:

```
https://alterhq.com/api/v1
```

### 3. List Available Models

```bash theme={null}
curl https://alterhq.com/api/models \
  -H "Authorization: Bearer YOUR_API_KEY"
```

## Model Naming Format

Models use the format: `Provider#Model-name`

Examples:

* `OpenAI#gpt-5` - Latest GPT-5
* `OpenAI#gpt-5-mini` - Lightweight GPT-5
* `Claude#claude-sonnet-4-6` - Latest Claude
* `Gemini#gemini-2.5-pro` - Latest Gemini

## Usage Example

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

client = OpenAI(
    api_key="YOUR_API_KEY",
    base_url="https://alterhq.com/api/v1"
)

response = client.chat.completions.create(
    model="OpenAI#gpt-5",
    messages=[
        {"role": "user", "content": "What is machine learning?"}
    ]
)

print(response.choices[0].message.content)
```

## Usage Limits

* **Daily Limit**: 200 requests per day under fair use
* **Throttling**: After 200 requests, throttled to 1 per 10 minutes
* **Budget Top-up**: Available for consistent access beyond fair use

## Next Steps

* [API Gateway Guide](/api-router/api-gateway) - Complete usage documentation
* [API Router for Development](/api-router/development) - SDK and code examples
* [App Integrations with API Router](/api-router/app-integrations) - Connect third-party apps
* [Model Naming Reference](/references/api-model-names) - Full model list
* OpenAPI Reference - Interactive API documentation