How To Send cURL POST Requests with Data and Headers

To send a curl post request, we can use the following syntax:

curl -X POST \
     -H "Headers" \
     -d "Body" \
     https://httpbin.dev/post

This snippet demonstrates the fundamental components of a curl post data request:

• -X: Defines the HTTP request method, POST in this instance.
• -H: Used for adding request headers, which are frequently necessary for POST requests.
• -d: Used for including the cURL post body, containing your payload data (JSON, XML, or form data).

Common cURL POST Request Examples

Let’s explore some typical scenarios for sending a curl post request.

cURL POST Request with JSON

To include a JSON body in a cURL POST request with JSON, utilize the -d option followed by the data object:

curl -X POST -H "Content-Type: application/json" -d '{"key1": "value1", "key2": "value2"}' https://httpbin.dev/post

In this example, we set the request Content-Type header and include the cURL request body in JSON format. The server returns the parsed request:

{
  "args": {},
  "headers": {
    ....
    "Content-Type": [
      "application/json"
    ],
  },
  "method": "POST",
  "data": "{\"key1\": \"value1\", \"key2\": \"value2\"}",
  "json": {
    "key1": "value1",
    "key2": "value2"
  }
}

cURL POST Request with XML

You can also transmit a cURL POST request with XML by modifying the header and body format:

curl -X POST \
     -H "Content-Type: application/xml"
     -d "1Box of Chocolate Candy"
     https://httpbin.dev/post

This method is frequently used for SOAP-based or legacy APIs that require XML payloads.

Sending Files with cURL POST

To upload files using cURL POST, we use the -F flag to send file data as multipart/form-data:

curl -X POST -F "file=@/file/path/file.img" https://httpbin.dev/post

Note: When uploading multiple files, use multiple -F flags. This approach is useful for form-based file upload endpoints.

Sending Form POST Requests

Form POST requests are frequently required to retrieve tokens or data behind forms. Let’s replicate this form example using cURL POST requests:

curl -X POST \
     -d 'custname=Webparsers&custtel=&custemail=&size=small&topping=cheese&delivery=13%3A45&comments=' \
     https://httpbin.dev/post

This technique is particularly valuable when interacting with APIs or web applications that use forms to receive input.

Authenticate cURL POST Requests

Let’s configure cURL POST requests to support basic HTTP authentication. For this purpose, we can use the basic option:

curl -X POST --user user:passwd --basic https://httpbin.dev/basic-auth/user/passwd

The response from the above cURL request confirms successful authentication:

{
  "authorized": true,
  "user": "user"
}

For comprehensive details on various authentication mechanisms with cURL requests, refer to our dedicated guide.

Further cURL Options

Sending cURL POST requests often requires additional configuration for the request. Here are supplementary cURL arguments and their usage:

Argument	Full Option	Description
-x	–proxy	Use proxy with cURL, either as HTTP or SOCKS
-Z	–parallel	Send multiple cURL requests in parallel
-L	–location	Make cURL follow request redirects
-O	–output	Save the response binary data to a local directory
-I	–head	Use the request HEAD HTTP method
-b	–cookie	Add request cookies
-v	–verbose	Sends the request in verbose mode, which include further debugging details
-k	–insecure	Skip SSL verification for HTTPs connection

For comprehensive details on sending requests with cURL, refer to our dedicated guide.