curl

1. Introduction

Designed to work without user interaction, curl is a tool for transferring data from or to a server. It supports these protocols:

DICT (Dictionary network | Port 2628)
FILE
FTP (Data transfer | Port 20, 21)
FTPS,
GOPHER,
GOPHERS,
HTTP,
HTTPS,
IMAP,
IMAPS,
LDAP,
LDAPS,
MQTT,
POP3,
POP3S,
RTMP,
RTMPS,
RTSP
SCP,
SFTP,
SMB,
SMBS,
SMTP,
SMTPS,
TELNET
TFTP

curl offers a busload of useful tricks like proxy support, user authentication, FTP upload, HTTP post, SSL connections, cookies, file transfer resume and more. As you will see below, the number of features will make your head spin.

    curl google.com -I

HTTP/1.1 301 Moved Permanently
Location: http://www.google.com/
Content-Type: text/html; charset=UTF-8
Content-Security-Policy-Report-Only: object-src 'none';base-uri 'self';script-src 'nonce-qYdV_FPHpEBv6vYwKNQrVA' 'strict-dynamic' 'report-sample' 'unsafe-eval' 'unsafe-inline' https: http:;report-uri https://csp.withgoogle.com/csp/gws/other-hp
Date: Thu, 04 Dec 2025 12:45:59 GMT
Expires: Sat, 03 Jan 2026 12:45:59 GMT
Cache-Control: public, max-age=2592000
Server: gws
Content-Length: 219
X-XSS-Protection: 0
X-Frame-Options: SAMEORIGIN