> For the complete documentation index, see [llms.txt](https://docs.chainrpc.io/chainrpc/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.chainrpc.io/chainrpc/networks/arbitrum/how-to/make-requests.md).

# Make requests

The Arbitrum API is a superset of the Ethereum JSON-RPC specification and supports all the [Ethereum JSON-RPC methods](/chainrpc/networks/ethereum/json-rpc-methods.md). When interacting with the API, you can expect all the usual fields, [and some extra ones](https://developer.offchainlabs.com/docs/differences_overview#json-rpc-api) used to display information unique to Arbitrum.

{% hint style="warning" %}
WebSocket calls are not supported when using the Arbitrum endpoints
{% endhint %}

## Call a JSON-RPC method

Use HTTPS to call a JSON-RPC method. In this example we use [`curl`](https://curl.se) to make the HTTPS request.

**Note**: Ensure that you replace `YOUR-API-KEY` with an API key from your [chainRPC dashboard](https://chainrpc.io/dashboard).

```bash
$ curl -X POST \
-H "Content-Type: application/json" \
--data '{"jsonrpc": "2.0", "id": 1, "method": "eth_blockNumber", "params": []}' \
"https://arb.chainrpc.io/v3/YOUR-API-KEY"
```

The result should look similar to the following:

```json
$ {"jsonrpc":"2.0","id":1,"result":"0x5fe1df"}
```