Getting Started with cURL
When building websites or backend applications, your code constantly communicates with servers.
For example:
A frontend asks for user data
A mobile app sends login details
A backend talks to another API
A website fetches product information
All of this happens through requests sent over the internet.
But how can developers manually send requests to servers without opening a browser?
That’s where cURL comes in.
In this blog, you’ll learn:
What cURL is
Why programmers use it
How to make your first request
Understanding requests and responses
Using cURL with APIs
Common beginner mistakes
First: What Is a Server?
Before understanding cURL, you need to understand what a server is.
A server is simply:
A computer that provides data or services to other computers.
Examples:
Google’s servers send search results
YouTube servers send videos
Instagram servers send posts and messages
When you open a website:
Your browser sends a request
The server responds with data
Browser → Server Communication
Browser
↓ Request
Server
↓ Response
Browser displays result
This request-response communication powers the internet.
Why Do Programmers Need to Talk to Servers Directly?
Browsers are convenient for normal users.
But developers often need more control.
For example:
Testing APIs
Sending data manually
Debugging backend systems
Checking server responses
Automating requests
Using a browser for all this can be difficult.
Developers need a direct communication tool.
That tool is cURL.
What Is cURL?
cURL is a command-line tool that lets you:
Send requests to servers directly from the terminal.
Think of cURL as:
- A way to talk to servers manually
Instead of clicking buttons in a browser:
- You type commands in the terminal
Real-Life Analogy
Imagine:
Browser = Full restaurant experience
cURL = Directly talking to the kitchen
cURL removes the visual interface and communicates directly.
What Does cURL Stand For?
cURL stands for:
Client URL
But beginners don’t need to memorize that.
The important idea is:
cURL sends HTTP requests from the terminal.
cURL → Server → Response Flow
Terminal
↓
cURL Request
↓
Server
↓
Response Data
↓
Displayed in Terminal
Your First cURL Request
Let’s start with the simplest possible example.
Fetch a Webpage
curl https://example.com
That’s it.
You just made your first cURL request.
What Happens Here?
cURL sends a request to the server
The server responds
cURL prints the response in the terminal
Example Response
You may see HTML like:
<!doctype html>
<html>
<head>
<title>Example Domain</title>
</head>
</html>
This is the webpage content returned by the server.
Understanding Request and Response
The internet mainly works using:
Requests
Responses
Request
A request means:
“Please give me something.”
Example:
GET https://example.com
Response
The server replies with:
Data
Status
Content
Example:
200 OK
plus webpage data.
Basic HTTP Structure
Client Request
↓
GET /users
Server Response
↓
200 OK
{
"name": "Alex"
}
What Is HTTP?
HTTP is the communication protocol used between:
Clients
Servers
cURL mainly works with HTTP requests.
Browser Request vs cURL Request
Browser
Browser
│
├── Sends request
├── Downloads images
├── Applies CSS
├── Runs JavaScript
└── Renders webpage
cURL
cURL
│
├── Sends request
└── Shows raw response
cURL focuses only on communication.
GET Requests in cURL
The default cURL request type is:
GET
GET requests are used to:
- Fetch data
Example:
curl https://jsonplaceholder.typicode.com/users
This fetches user data from an API.
What Is an API?
An API allows applications to communicate with each other.
You can think of APIs as:
- Digital waiters between systems
Frontend apps ask APIs for data.
Using cURL with APIs
cURL is heavily used for API testing.
Example:
curl https://jsonplaceholder.typicode.com/posts/1
Example response:
{
"id": 1,
"title": "Sample Post"
}
The server returns JSON data.
Why This Is Useful
Developers can:
Test APIs quickly
Verify server behavior
Debug backend issues
without building a frontend first.
Understanding GET Requests
GET requests are mainly for:
- Fetching information
Examples:
Fetch users
Fetch products
Fetch posts
GET requests usually do not modify server data.
POST Requests in cURL
POST requests are used to:
Send data to the server
Example uses:
Login
Register
Create posts
Upload forms
Simple POST Example
curl -X POST https://example.com/api
This tells cURL:
- Use POST instead of GET
Beginner-Friendly Understanding
| Request Type | Purpose |
|---|---|
| GET | Fetch data |
| POST | Send data |
That’s enough for beginners initially.
Real-World Example
Imagine a login form.
Frontend sends:
Username
Password
Backend verifies credentials and responds.
cURL allows developers to simulate this manually.
Where cURL Fits in Backend Development
Backend developers use cURL constantly for:
API testing
Debugging
Microservices communication
Learning APIs
Checking server responses
Backend Development Flow
Frontend App
↓
API Request
↓
Backend Server
Developer can test using:
cURL
Common Beginner Mistakes
1. Forgetting the URL
Wrong:
curl
Correct:
curl https://example.com
2. Confusing Browser Output with API Output
Many APIs return:
JSON not:
Beautiful webpages
That is normal.
3. Thinking cURL Is Only for Backend Developers
Frontend developers also use cURL frequently to:
Test APIs
Understand responses
4. Being Afraid of Terminal Tools
Many beginners feel:
- The terminal looks scary
But cURL commands are often very simple.
Start with:
- Basic GET requests
Confidence grows quickly.
Why Developers Love cURL
Fast
No browser needed.
Lightweight
Works directly from terminal.
Great for Testing APIs
Extremely useful during backend development.
Available Everywhere
Most systems already include cURL.
Practice Exercises
Exercise 1
Fetch a webpage:
curl https://example.com
Observe:
- The returned HTML
Exercise 2
Fetch API data:
curl https://jsonplaceholder.typicode.com/users
Observe:
- JSON response
Exercise 3
Try a POST request:
curl -X POST https://jsonplaceholder.typicode.com/posts
Observe:
- Server response
Beginner Mental Model
The simplest way to think about cURL:
cURL = Manual communication with servers
Instead of:
- Clicking through a browser
You directly send requests yourself.
Final Thoughts
cURL is one of the simplest and most useful tools in backend development.
The key ideas are:
Servers respond to requests
cURL sends requests from the terminal
GET fetches data
POST sends data
APIs can be tested without a frontend
You do not need to memorize dozens of flags initially.
Start simple:
Fetch webpages
Call APIs
Read responses
Once comfortable, cURL becomes an incredibly powerful debugging and development tool.