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

# REST API overview

> Base URL, endpoint groups, and authentication for the Radion REST API.

The Radion API is a REST API. You use it to read Polymarket on-chain data: markets, events, and the orderbook. All the data comes from Radion's own on-chain indexer.

## Base URL

```text theme={null}
https://api.radion.app
```

## Endpoint groups

| Group              | What it does                                             |
| ------------------ | -------------------------------------------------------- |
| **Authentication** | Look at the API key you are using                        |
| **Events**         | List events and read one event by numeric id or slug     |
| **Markets**        | List markets and read one market by condition id or slug |
| **Search**         | Search events, topics, and profiles by text              |
| **Orderbook**      | Get the current midpoint price for an outcome token      |
| **Health**         | Check that the API is up                                 |

## Authentication

You need an API key for all `/v1/*` requests. Keys are free. Sign in at [radion.app/dashboard](https://radion.app/dashboard) to make one. Send your key in the `X-API-Key` header:

```http theme={null}
X-API-Key: YOUR_API_KEY
```

See [Authentication](/api/authentication) for more, and [Rate limits](/api/rate-limits) for how many requests each plan allows.