> ## 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 Model Reference

> Complete list of AI models available through the Alter API Router

This reference lists all AI models available through the Alter API Router. Use these model names when making API requests.

## Model Naming Format

All models follow the format: `Provider#Model-name`

For example: `OpenAI#gpt-5`, `Claude#claude-sonnet-4-6`

## OpenAI Models

| Model Name          | Description           | Context Window |
| ------------------- | --------------------- | -------------- |
| `OpenAI#gpt-5`      | Latest GPT-5 model    | 128K           |
| `OpenAI#gpt-5-mini` | Lightweight GPT-5     | 128K           |
| `OpenAI#gpt-5-nano` | Fastest GPT-5 variant | 128K           |
| `OpenAI#o3`         | Advanced reasoning    | 200K           |
| `OpenAI#o4-mini`    | Efficient reasoning   | 200K           |

## Claude (Anthropic) Models

| Model Name                 | Description          | Context Window |
| -------------------------- | -------------------- | -------------- |
| `Claude#claude-sonnet-4-6` | Latest Claude Sonnet | 200K           |
| `Claude#claude-opus-4-6`   | Most capable Claude  | 200K           |
| `Claude#claude-haiku-4-6`  | Fast Claude variant  | 200K           |

## Gemini (Google) Models

| Model Name                     | Description         | Context Window |
| ------------------------------ | ------------------- | -------------- |
| `Gemini#gemini-2.5-pro`        | Most capable Gemini | 1M             |
| `Gemini#gemini-2.5-flash`      | Fast Gemini         | 1M             |
| `Gemini#gemini-2.5-flash-lite` | Lightweight Gemini  | 1M             |

## Mistral Models

| Model Name                     | Description          | Context Window |
| ------------------------------ | -------------------- | -------------- |
| `Mistral#mistral-large-latest` | Most capable Mistral | 128K           |
| `Mistral#mistral-small-latest` | Efficient Mistral    | 128K           |
| `Mistral#codestral-2501`       | Code specialist      | 32K            |
| `Mistral#pixtral-large-latest` | Vision capable       | 128K           |

## Perplexity Models

| Model Name                   | Description         | Context Window |
| ---------------------------- | ------------------- | -------------- |
| `Perplexity#sonar`           | Web-aware model     | 128K           |
| `Perplexity#sonar-pro`       | Advanced web search | 128K           |
| `Perplexity#sonar-reasoning` | Reasoning with web  | 128K           |

## Alter Models

| Model Name    | Description                      |
| ------------- | -------------------------------- |
| `Alter#best`  | Automatically selects best model |
| `Alter#fair`  | Cost-effective option            |
| `Alter#light` | Fastest response                 |

## Usage Examples

### Python

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

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

# Use GPT-5
response = client.chat.completions.create(
    model="OpenAI#gpt-5",
    messages=[{"role": "user", "content": "Hello!"}]
)
```

### cURL

```bash theme={null}
curl https://alterhq.com/api/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "OpenAI#gpt-5",
    "messages": [{"role": "user", "content": "Hello!"}]
  }'
```

## Model Selection Tips

**For Speed**

* `Alter#light`
* `OpenAI#gpt-5-nano`
* `Gemini#gemini-2.5-flash-lite`

**For Quality**

* `Alter#best`
* `OpenAI#gpt-5`
* `Claude#claude-opus-4-6`
* `Gemini#gemini-2.5-pro`

**For Coding**

* `OpenAI#gpt-5`
* `Mistral#codestral-2501`
* `Claude#claude-sonnet-4-6`

**For Vision**

* `OpenAI#gpt-5`
* `Gemini#gemini-2.5-pro`
* `Mistral#pixtral-large-latest`

**For Cost**

* `Alter#fair`
* `Alter#light`
* `OpenAI#gpt-5-nano`