# All About cURL?

## What is cURL ?

cURL is basically a **command line tool**, it is use for **transferring data from server**. cURL means **client URL**. cURL is available in all platforms. supports different **protocols like HTTP, HTTPS etc**.

## What is server ?

Server is a software or hardware which processes client requests and gives them response. This follows client-server architecture.

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1768978834030/833b6228-faa6-4314-a3d3-6df033f5a844.png align="center")

## why we use cURL ?

1. cURL is super portable with every device.
    
2. Programmer used cURL for testing end points of a api.
    
3. providing details of exactly what has been sent/received, which is helpful for debugging.
    
4. Efficient Data Transfer, it is extremely light weight.
    
5. With support for SSL and TLS, cURL facilitates secure data transfer.
    

## Basic Syntax of cURL:

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## common options cURL have:

| **Options** | **usage** |
| --- | --- |
| \-d | sending data with the request. |
| \-h | sending HTTP header with the request. |
| \-i | Includes the HTTP header in the output. |
| \-X | Specifies the HTTP request method (POST,GET, Etc) |
| \-T | upload file with the request |
| \-O | download a file |

to have more information about cURL options

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## Sending API request by cURL:

1. An **endpoint**, which is the address (URL) to which we are sending the request.
    
2. An **HTTP method**. The most common methods used are GET, POST, PUT and DELETE.
    
3. **Headers**, which contain metadata about the request.
    
4. **Body**, which is the message body and contains the data that we want to send.
    

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1768979747339/347a919d-ec08-42f0-8e30-d14f01fb5c5f.png align="center")

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<div data-node-type="callout-text">curl -X POST -H "Content-Type: application/json" -d '{"username":"user", "password":"pass"}' <a target="_self" rel="noopener noreferrer nofollow" href="https://api.example.com/login" style="pointer-events: none">https://api.example.com/login</a></div>
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## Fetching Web page by cURL:

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![](https://cdn.hashnode.com/res/hashnode/image/upload/v1768979967006/52e53dec-55b8-4cf8-8730-40e5eedd5a80.png align="center")

**it gives the html of that website.**

## what is response means?

when we give a request to server by cURL it gives some replies. This reply is called response.

### A response typically have 3 Main parts:

1. **statuscode**: A **status code** is a **number** sent by the server to tell **what happened** with request. Its like exam result.
    
2. **Data(text/JSON/HTML)**
    
3. **Headers(Extra INFO)**
    

![State the core components of an HTTP response ? - GeeksforGeeks](https://media.geeksforgeeks.org/wp-content/uploads/20210905094321/StructureOfAHTTPResponse-660x374.png align="left")

## what is HTTP methods?

HTTP methods is use for define what action the client want to performs. This is the core part of client-server architecture.

**some basic HTTP methods:**

1. GET: **Fetch data** from the server
    
2. POST: **Send data** to the server
    
3. PUT: **Update or replace** existing data
    

## cURL vs Browser

**Automated Testing**  
cURL is perfect for programmatically testing APIs and web services. It allows developers to send requests and validate responses without manual interaction.

**Data Transfer Tasks**  
Whether downloading files or uploading data, cURL works seamlessly inside scripts and automated workflows, making it highly efficient.

**Headless Environments**  
On servers or systems without a graphical interface, cURL becomes an essential tool for performing web requests directly from the command line.

**Development & Debugging**  
With its verbose options, cURL helps developers inspect HTTP requests and responses in detail—something browsers don’t easily expose.