> ## 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 Operations & Troubleshooting

> Model selection, limits, reliability, and common fixes for Alter API Router

## Model selection quick guide

**Speed**

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

**Quality**

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

**Coding**

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

**Web search**

* `Perplexity#sonar`
* `Perplexity#sonar-pro`

## Usage limits

Under fair use:

* Daily limit: `200` requests/day
* After limit: throttled to `1 request / 10 minutes`
* For steady higher volume: top up budget

<Note>
  API Router is designed for personal and low-volume workloads. For multi-user products or heavy agentic traffic, use dedicated provider infrastructure.
</Note>

## Common issues

### Models not listed

* Manually set the model to `Provider#Model-name`
* Verify API key is valid
* Check client supports model listing endpoints

### Authentication errors

* Confirm `Authorization: Bearer YOUR_API_KEY`
* Confirm endpoint is `https://alterhq.com/api` or `/api/v1`
* Confirm your account is active

### Connection issues

* Use an OpenAI-compatible client
* Verify network access to `alterhq.com`

### High latency

* Try lighter models (`OpenAI#gpt-5-nano`, `Alter#light`)
* Use streaming for long outputs

## Best practices

1. Keep API keys in env vars (never hardcode)
2. Monitor request volume and error rates
3. Match model capability to task complexity
4. Implement retries with backoff
5. Use lower-cost models for routine workloads

## Related

* [API Gateway & Router Service](/api-router/api-gateway)
* [API Router for Development](/api-router/development)
* [Models Not Listed in API Gateway](/common-issues/models-not-listed-in-api-gateway)