The Internet is based on sending and receiving requests. It is the backbone of the process of transferring information over internet protocols. And hidden inside this magical process lies cURL.
You could say cURL is everywhere, yet only some know exactly what’s the deal with it. A quick Google search will show you all sorts of words, instructions, and terms only programming experts would understand.
And for that, why not start with the basics and find out what cURL is in the first place?
We will give you an introduction to this command and discuss why it is so versatile and popular. Who knows, maybe you will enjoy using it and reap its automatization benefits.
What is cURL?
cURL (client URL) is an open-source command line tool we can use to transfer data between servers. Open source means cURL is made freely available and may be redistributed and modified. It is this open-source feat that makes cURL a cross-platform library (libcurl). This means that it can work with nearly all modern operating systems such as Linux distributions, Windows, and Mac.
cURL is used in almost every situation that requires sending or receiving data via internet protocols. What makes this command great is its benefits for automation, since it is designed to work without user interaction. Besides, it supports nearly every internet protocol:
- DICT – Dictionary Network Protocol;
- FTP, FTPS* – File Transfer Protocol;
- GOPHER, GOPHERS*;
- HTTP, HTTPS* – Hypertext Transfer Protocol;
- IMAP, IMAPS* – Internet Message Access Protocol;
- LDAP, LDAPS* – Lightweight Directory Access Protocol;
- MQTT – Message Queuing Telemetry Transport;
- POP3, POP3S* – Post Office Protocol version 3;
- RTMP, RTMPS* – Real-Time Messaging Protocol;
- RTSP – Real-Time Streaming Protocol;
- SCP – Secure Copy;
- SFTP – SSH File Transfer Protocol;
- SMB, SMBS* – Server Message Block;
- SMTP, SMTPS* – Simple Mail Transfer Protocol;
- TFTP – Trivial File Transfer Protocol.
(The only difference between a protocol and its alternative ending in ‘-s’ is the fact that the latter has an extra SSL/TLS security layer.)
What does cURL do?
At its core, cURL is used to transfer data through internet protocols. Plain and simple. Everything else is outside its scope. But this does not mean cURL is not powerful enough to run lots of commands.
The syntax looks like this:
curl [options] [URL…]
The most basic command for cURL is to type the command followed by the URL, as in:
This should display the content of the URL in the command prompt of your device. You can also do that for multiple URLs, which makes it easier to retrieve data rather than extracting it manually.
cURL accepts a great range of options, which makes it an incredibly versatile command. There are a lot of cURL commands that you can use depending on your needs, and sometimes it might seem overwhelming. But luckily, you can start by literally asking your console for help.
How to use cURL?
Windows, macOS, and most Linux distributions already integrate cURL. However, for older versions, you might need to download and install it.
To use cURL simply open up the terminal (in this case, Windows Command Prompt) and type ‘’curl’’. The result should display “curl –help”, a command you can type and run to get a list of the most used cURL options, listed in categories.
Since there are dozens of commands you can run, the “–help category” will help you get an overview of all categories. Adding to that, typing and running ”–help all” will list all the possible cURL commands you can run.
A cURL command can be combined by adding the listed flags and typing in an URL. Flags can be either short (like -o, -L) or long (like –upload-file). These flags are differentiated by the use of single (-) or double (–) dashes.
Do not worry if this sounds like alien speech. Fortunately, there are great resources you can consult to get a better understanding of what each command does.
Popular cURL uses
cURL would probably help you with every possible need when it comes to sending and receiving data via internet protocols. Here are the most popular use cases for running cURL:
cURL was initially developed for HTTP, which lets us send all the usual HTTP-based requests (like POST, GET, or PUT). We usually send requests to ask a web server to store or retrieve for us information.
It should be noted that most websites will deny such requests from unauthorized users. For that, you can use an API (Application Programming Interface).
Retrieving a particular byte-range
cURL can be used to get only a particular byte range of a document. In simpler terms, you can run the command to retrieve only a part of a document.
Saving or resuming a download
You can easily save the content of the URL to a file via cURL. Or, if your download stops in the middle for some reason, it’s just as quick and easy to rewrite the initial command you initially ran.
Using it with proxies
Combining cURL commands with proxies can bring many benefits. For example, it can help you better manage data requests from different geolocations. Besides, it can help you manage more data processes at the same time more easily.
Making web scraping more efficient
You can use cURL to automate the repetitive processes of web scraping, helping you avoid time-consuming tasks. If done right, cURL can help you get exactly what you need from the website you wish to scrape.
This also works wonders when you combine it with proxies. ”Curling” with proxies is one of the most formidable ways of improving data collection.
Verbose with cURL
If you are in the middle of a process you want to check on, cURL can be used to provide detailed information about that process. Because of that, it can greatly help with debugging complex situations.
Conclusion – Why does cURL matter
As the Internet relies more and more on automated tasks, it is important to know how to perform the needed operations fast and efficiently.
cURL is an incredibly versatile tool designed to work with almost all internet protocols. Thanks to this, it can perform dozens of operations and has many practical applications.
Sending requests, asking for detailed information on a process, and using it with proxies, or for data collection is just the tip of the iceberg. The more familiar you get with cURL, the easier it will be for you to simplify your repetitive tasks.