cURL is a powerful command-line tool used to transfer data with URLs. It supports multiple protocols including HTTP, HTTPS, FTP, and more. Developers often use cURL to test APIs, debug requests, and manage data transfers. In this guide, we’ll cover how to view HTTP headers and send custom headers with cURL.

Show HTTP Response Headers with cURL

To display only the response headers, use the -I (or --head) option:

curl -I https://example.com

This command sends a HEAD request and shows headers like:

HTTP/2 200 
date: Sat, 13 Sep 2025 08:00:00 GMT
content-type: text/html; charset=UTF-8
server: nginx

Show Headers with the Response Body

If you want both headers and the body, use the -i option:

curl -i https://example.com

The output will include headers first, followed by the HTML body of the response.

Send Custom HTTP Headers with cURL

To send custom headers, use the -H (or --header) option:

curl -H "Accept: application/json" https://api.example.com/data

You can pass multiple headers by repeating the -H flag:

curl -H "Content-Type: application/json" \
     -H "Authorization: Bearer your_token_here" \
     https://api.example.com/data

Send POST Request with Headers

When sending a POST request with headers:

curl -X POST https://api.example.com/login \
     -H "Content-Type: application/json" \
     -d '{"username":"user","password":"pass"}'

This example sends JSON data with custom headers to an API endpoint.

Verbose Output (Debugging)

For debugging, use the -v option to see detailed request and response headers:

curl -v https://example.com

It prints the full communication including request headers, making it useful for troubleshooting.

Quick Summary

• -I → Show only response headers
• -i → Show headers + body
• -H → Send custom headers
• -X → Specify request method (GET, POST, PUT, DELETE)
• -v → Verbose mode (request + response headers)

Conclusion

Using cURL Post, you can easily send and view HTTP headers for debugging and API testing. Whether you need to check server response headers, send authentication tokens, or test custom requests, cURL provides a simple yet powerful way to handle HTTP communication directly from the command line.