cURL 시작하기

Source: Dev.to

Introduction

In this article we’ll cover:

• What a server is and why we need to talk to it
• What cURL is (in very simple terms)
• Why programmers use cURL
• Making your first request using cURL
• Understanding requests and responses with cURL
• Common mistakes beginners make while using cURL

What a Server Is

Think of a server like a friend you ask for money.

• If the friend is in a good mood and has money, they say “Sure”.
• Otherwise, they say “No”.

A server works in a very similar way.

A server is a hardware or software system that receives requests over a network, processes them, and sends back a response.

Every time you open a website, upload a photo, or log in to an app you’re talking to a server. Servers are important because they allow us to:

• Get data – fetch posts, videos, products, etc.
• Send data – forms, messages, login details
• Update data – edit profile, change password
• Delete data – remove posts or accounts

For example, you cannot upload a photo to social media without communicating with a server.

What cURL Is

cURL stands for Client URL. It is a command‑line tool (like ping or ipconfig) used to send requests and transfer data between your computer and a server using a URL.

You can run cURL from any Command Line Interface (CLI), such as:

• Command Prompt (cmd)
• PowerShell
• Terminal (macOS / Linux)
• Warp

In simple words: cURL lets you talk to servers directly from the command line.

Why Programmers Use cURL

• Allows quick HTTP requests
• Supports all common methods: GET, POST, PUT, DELETE, etc.
• Lightweight and fast
• No browser or UI required – just commands
• Frequently used by backend developers to test APIs

Making Your First Request

Open a CLI on your device and run:

curl https://google.com

You’ll see the raw HTML returned by the server.

GET Request

A GET request retrieves data from a server.

curl https://dummyjson.com/products

The response is a list of products in JSON format.

POST Request

A POST request sends or updates data on a server.

curl -X POST https://httpbin.org/anything

The server responds with details about the request it received.

Understanding Requests and Responses

When you use cURL:

1. You send a request (URL + method + optional data)

2. The server processes it

3. The server sends a response, which includes:

   • Status code (e.g., 200, 404, 500)
   • Headers
   • Response body (data or message)

This request–response cycle is the foundation of APIs.

Common Mistakes to Watch Out For

• ❌ Writing URLs incorrectly or without quotes when required
• ❌ Ignoring the HTTP status code in the response
• ❌ Sending invalid JSON data
• ❌ Forgetting flags like -X, -H, or -d
• ❌ Mixing up GET and POST requests

Conclusion

cURL might look scary at first, but once you understand it, it becomes a powerful tool for learning how servers and APIs actually work. If you’re a beginner in backend development, learning cURL is 100 % worth it.

Happy coding 🚀