What is cURL? Sending Messages to Servers Without a Browser
What is cURL
cURL which stands for client URL and it can be written as curl. It is a command line tool used to transfer file with a URL syntax. It supports a number of protocols including HTTP, HTTPS, FTP and many more. While a browser is designed to show you a webpage but cURL is designed to give you the raw data.
Why Do Programmers Need cURL?
You might wonder: Why should we use terminal if browsers are already in the market. Programmers use cURL because:
It's Fast: You don't have to wait for images to load.
It’s Automatable: You can write a script that uses cURL to check a website every hour automatically.
It’s Great for APIs: When you're building an app that needs weather data or stock prices, before writing your actual code you use cURL to check your API.
Making Your First Request
Open your terminal (Command Prompt on Windows or Terminal on Mac/Linux) and type this simple command:
curl https://www.google.com
When you make a simple curl request by default it will always takes a GET request. Such as we are sending a cURL request to google.com so it asks the server for the default information about this URL and Google replies with the HTML data
Understanding Request and Response
Request: Any time we send a cURL request to google.com behind the scene cURL sends an HTTP request as a GET request to google.com.
Response: This is what server sends back to us means we receive in return. It usually includes two thing status code and body.
Status Code: A number telling you if it worked (e.g., 200 OK means success, 404 Not Found means the page is missing).
Body: The actual data that we get in return (i.e: HTML, JSON or TEXT).
Talking to APIs (GET vs. POST)
In the world of web development we mostly do two things get information or send information
The GET Request
The GET request is used to fetch data from the server as we know cURL uses GET request by default to fetch the data from the servers such as checking the current weather from an API.
The POST Request
You don't always get data sometimes you need to send data so you need to use POST request which is used to send data such as submitting a form or a comment on a blog post.
Common Mistakes Beginners Make
Forgetting the protocol like (http:// or https://).
Missing headers when calling APIs - Forgetting Content-Type or Authorization is a common issue.
Sending JSON without -d. Writing JSON but forgetting -d means no body is sent at all.
Using single quotes wrong on Windows - Single quotes work in Linux/macOS, but can break in Windows CMD.
Assuming curl behaves like Postman - Curl is raw and strict. No auto headers, no body formatting, no retries unless you ask for it.
