HTTP request consists of a request line, headers, and a body. The request line contains the HTTP method, the URL, and the HTTP version. The headers contain additional information about the request, such as the Content-Type and Accept headers. The body contains the data sent in the request.

Data can be sent in an HTTP request in several ways. The most common ways are:

  1. As URL parameters in a GET request.
  2. As form data in a POST request.
  3. As JSON data in a POST request.
  4. As multipart/form-data in a POST request.
  5. As form data in a PUT request.

cURL allows you to send data in an HTTP request. cURL supports sending data in a variety of HTTP methods, such as POST, GET, PUT, and DELETE. It also supports sending data in a variety of formats, such as JSON, URL-encoded, and multipart/form-data.

Steps to send data in an HTTP request with cURL:

  1. Open the terminal.
  2. To send data as URL parameters in a GET request, use:

    $ curl "https://www.example.com/api?param1=value1&param2=value2"
  3. To send data as form data in a POST request, use:

    $ curl -d "param1=value1&param2=value2" https://www.example.com/api

    With the -d flag, cURL uses POST by default.

  4. If you need to send JSON data, use the following structure:

    $ curl -X POST -H "Content-Type: application/json" -d '{"key1":"value1", "key2":"value2"}' https://www.example.com/api

    Ensure that the Content-Type header is set to application/json when sending JSON payloads.

  5. To send data in a PUT request, use:

    $ curl -X PUT -d "param1=value1&param2=value2" https://www.example.com/api
  6. For sending data as multipart/form-data (such as file uploads), use:

    $ curl -F "file=@path_to_file" https://www.example.com/upload

    The -F flag makes cURL emulate a filled-in form in which a user has pressed the submit button. This causes cURL to POST data using the Content-Type multipart/form-data.

  7. To customize headers when sending data, use the -H flag followed by the header:

    $ curl -H "Authorization: Bearer YOUR_TOKEN" -d "param=value" https://www.example.com/api
  8. If you're dealing with an endpoint with SSL issues and wish to bypass them (mostly in development environments), use the –insecure flag:

    $ curl --insecure -d "param=value" https://www.example.com/api

    Using –insecure or its shorthand -k bypasses SSL certificate checks. This is risky in production environments.