> For the complete documentation index, see [llms.txt](/llms.txt).

# curl

The [Client Uniform Resource Locator (curl)](https://curl.se/) command line tool sends API requests via URLs and returns responses.

Requests to Infura APIs commonly use curl.

info

We recommend the resource [_Everything curl_](https://everything.curl.dev).

### Install curl[​](#install-curl "Direct link to Install curl")

Your operating system may include curl, or you may need to [download and install it](https://everything.curl.dev/install).

### curl commands[​](#curl-commands "Direct link to curl commands")

Many Infura requests take the form:

```
curl https://mainnet.infura.io/v3/<YOUR-API-KEY> \
  -X POST \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc": "2.0", "method": "eth_blockNumber", "params": [], "id": 1}'

```

The code snippet above is an API call to Infura's Ethereum mainnet endpoint.

It requests the latest block number using the method `eth_blockNumber`.

### curl analysis[​](#curl-analysis "Direct link to curl analysis")

Let's step through each line of the code snippet to understand what's happening.

The first line uses the `curl` command to send a request to the URL `https://mainnet.infura.io/v3/<YOUR-API-KEY>`.

#### curl command[​](#curl-command "Direct link to curl command")

```
curl https://mainnet.infura.io/v3/<YOUR-API-KEY> \

```

info

Replace `<YOUR-API-KEY>` with a specific [API key](/developer-tools/dashboard/get-started/create-api/).

#### `-X` flag[​](#-x-flag "Direct link to -x-flag")

The `-X` flag specifies a common [HTTP method](https://www.w3schools.com/tags/ref%5Fhttpmethods.asp).

```
-X POST \

```

#### `-H` flag[​](#-h-flag "Direct link to -h-flag")

The `-H` or `--header` flag specifies [header](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers) information.

The example specifies the `Content-Type` to be `application/json` which means the requested resource is a JavaScript Object Notation (JSON) object.

```
-H "Content-Type: application/json" \

```

#### `-d` flag[​](#-d-flag "Direct link to -d-flag")

The `-d` or `--data` flag specifies more information sent along with the curl request.

In the example, the data object is a list of key value pairs in JSON format. This follows the [JSON RPC 2.0 specification](https://www.jsonrpc.org/specification) which requires the four specific keys seen here.

The `method`, `params`, and `id` values are modifiable.

The `jsonrpc` value is required by the specification.

```
-d '{"jsonrpc": "2.0", "method": "eth_blockNumber", "params": [], "id": 1}'

```

#### Running curl[​](#running-curl "Direct link to Running curl")

Enter curl code in a terminal window, or a command line tool from your computer's operating system and click return.

#### Output[​](#output "Direct link to Output")

curl returns a response object if the request is successful.

```
{"jsonrpc": "2.0", "id": 3, "result": "0xe0a763"}

```