Getting Started with cURL
Whenever you open a website, submit a form, or load data in an app, your computer is communicating with a server somewhere on the internet.
A server is simply a computer designed to store information and respond to requests from other machines.
For example:
When you visit a website, your browser asks a server for a webpage.
When a mobile app loads data, it requests information from an API server.
When developers test an API, they send requests to a server.
Normally, your browser handles these requests automatically. But developers often want a simpler way to send requests directly from the command line.
That’s where cURL comes in.
What Is cURL?
cURL is a command-line tool that lets you send requests to a server and receive responses.
In simple terms:
cURL allows you to communicate with a server directly from your terminal.
Instead of opening a browser, you can type a command and ask a server for data.
Developers use cURL to:
test APIs
fetch data from servers
debug backend systems
automate network requests
Because it works directly from the terminal, cURL is one of the most widely used tools in development and DevOps.
Why Programmers Need cURL
During development, programmers often need to check how a server responds.
For example, you might want to:
see if an API endpoint works
check the data returned by a server
test a POST request before writing code
debug an error in a backend service
Instead of building a full frontend just to test an API, developers can simply use cURL.
It allows you to quickly ask a server:
"Hey server, can you send me this data?"
And the server replies with a response.
This makes debugging and testing much faster.
Making Your First Request Using cURL
The simplest thing you can do with cURL is fetch a webpage.
Example command:
curl https://example.com
What happens here?
cURL sends a request to the server at
example.comThe server processes the request
The server sends back a response
cURL prints the response in the terminal
The output is usually the HTML content of the webpage.
So instead of seeing the webpage visually like in a browser, you see the raw response from the server.
Understanding Request and Response
Whenever you communicate with a server, two things happen:
Request – your computer asks the server for something
Response – the server sends back the result
This interaction is the foundation of how the web works.
Basic Flow
The response usually contains:
Status code (whether the request succeeded)
Headers (metadata about the response)
Body (the actual data returned)
Example response idea:
Status: 200 OK
Data: HTML page or JSON data
The status code tells you whether the request was successful.
Some common ones:
| Status Code | Meaning |
|---|---|
| 200 | Request successful |
| 404 | Resource not found |
| 500 | Server error |
Using cURL to Talk to APIs
Many modern applications rely on APIs.
An API allows one program to request data from another program.
For example:
Weather apps fetch weather data from an API
Mobile apps request user data from a backend server
Websites load product data from APIs
cURL makes it easy to test these APIs.
Example GET Request
A GET request asks the server for information.
Example:
curl https://api.github.com
This sends a request to GitHub’s API and returns information about the API.
GET requests are used to:
retrieve data
fetch resources
load information
Example POST Request
A POST request sends data to a server.
Example:
curl -X POST https://example.com/api
POST requests are commonly used for:
submitting forms
creating new records
sending data to APIs
At the beginner stage, the key idea is simply:
GET → receive data
POST → send data
Common Mistakes Beginners Make with cURL
When starting with cURL, beginners often run into a few common issues.
1. Forgetting the URL
Every cURL command must include a valid URL.
Example mistake:
curl
Correct:
curl https://example.com
2. Confusing Browser Output with API Output
Browsers render webpages visually, but cURL shows raw responses.
So instead of seeing a webpage layout, you’ll see:
HTML
JSON
text data
This is expected.
3. Using Too Many Options Too Early
cURL has many powerful flags and options, but beginners don’t need most of them right away.
Start with simple commands like:
curl URL
curl -X POST URL
Once you’re comfortable, you can explore more advanced options.
Where cURL Fits in Backend Development
cURL is widely used in development workflows.
Backend developers use it to:
test API endpoints
check server responses
debug production services
DevOps engineers use cURL to:
monitor services
test network connectivity
automate requests in scripts
Even many backend tools and libraries internally mimic what cURL does — sending HTTP requests and processing responses.
Understanding cURL helps developers better understand how clients and servers communicate.
Quick Revision
| Concept | Explanation |
|---|---|
| cURL | Tool for sending requests from the terminal |
| Server | Computer that processes requests and returns responses |
| Request | Message sent to a server |
| Response | Data returned by the server |
| GET | Used to retrieve data |
| POST | Used to send data |
Conclusion
cURL is one of the simplest tools for understanding how communication with servers works.
By sending requests directly from the terminal, you can see exactly how servers respond without needing a browser or application interface.
For developers working with APIs and backend systems, learning cURL provides a strong foundation for understanding HTTP communication and debugging network requests.
Once you're comfortable with the basics, you can explore more advanced features like headers, authentication, and request debugging.
