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

# Authentication

> Bearer token authentication with ltx_ API keys.

All authenticated endpoints require:

```
Authorization: Bearer ltx_your_api_key
```

Keys are generated at `POST /v1/register` — they are shown **once** and cannot be retrieved again.

## Key Rotation

Rotate your key with `POST /v1/keys/rotate`. The old key is invalidated immediately.

## Free Tier Limits

Free tier: **300 lifetime calls**. Once used, upgrade to Pro via `POST /v1/billing/setup`.

Check your usage at `GET /v1/billing`.