> ## Documentation Index
> Fetch the complete documentation index at: https://docs.0xradar.app/llms.txt
> Use this file to discover all available pages before exploring further.

# Authentication

> API keys, tiers, and how to authenticate requests

# Authentication

0xRadar uses an API key passed in the `X-API-Key` header. All `v1` endpoints except `/health` and `/chains` require authentication.

## Getting an API key

1. Sign up at [0xradar.app](https://0xradar.app)
2. Navigate to **Dashboard → API Keys**
3. Click **Generate Key**
4. Copy the key — it is shown only once

<Warning>
  Store your API key in a secrets manager. Never commit it to version control.
</Warning>

## Using the key

```bash theme={null}
curl -H "X-API-Key: 0xr_pro_YOUR_KEY_HERE" \
  https://api.0xradar.app/v1/wallet/0x.../balances?chain=ethereum
```

<Note>
  Query parameter `?api_key=` is **not supported** for security reasons (URL exposure in logs, browser history).
</Note>

## Tiers

| Tier | Rate Limit       | Daily Cap   | Best For                                |
| ---- | ---------------- | ----------- | --------------------------------------- |
| Free | 10 requests/min  | 100/day     | Prototyping, personal dashboards        |
| Dev  | 100 requests/min | 10,000/day  | Startups, small integrations            |
| Pro  | 600 requests/min | 100,000/day | Production apps, high-frequency polling |

Tier assignment is tied to your API key. Upgrade or downgrade from the Dashboard.

## Error responses

| Status                  | Meaning                         | Resolution                                 |
| ----------------------- | ------------------------------- | ------------------------------------------ |
| 401 Unauthorized        | Missing or invalid key          | Check header spelling and key validity     |
| 403 Forbidden           | Key valid but tier scope denied | Upgrade tier                               |
| 429 Too Many Requests   | Rate limit exceeded             | Back off and retry with exponential jitter |
| 503 Service Unavailable | Rate limiter temporarily down   | Retry after 5-10 sec                       |

## Next steps

* Review [Rate Limits](/getting-started/rate-limits) for headers and retry logic
* Browse the [API Reference](/api/health)