How to Use PHP cURL for HTTP Requests

Introduction

cURL (Client URL) is a powerful tool in PHP for making HTTP requests to external servers, commonly used for API integration, web scraping, and remote data retrieval. It supports various HTTP request methods, including:

✅ GET – Retrieve data from an API.
✅ POST – Send data to a server.
✅ PUT – Update an existing resource.
✅ PATCH – Partially update a resource.
✅ DELETE – Remove a resource.

In this guide, you’ll learn how to use cURL to execute these HTTP requests with practical examples.

Setting Up cURL in PHP

Before using cURL, ensure it is enabled in PHP. Run the following command to check:

php -m | grep curl

If cURL is not installed, enable it in php.ini by uncommenting the following line:

extension=curl

Now, restart your web server to apply the changes.

1. Making a GET Request with cURL

A GET request is used to retrieve data from a server.

Example: Fetching Data from an API

$url = "https://jsonplaceholder.typicode.com/posts/1";  

$ch = curl_init($url);  
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);  

$response = curl_exec($ch);  
curl_close($ch);  

echo $response;

✅ Key cURL Option: CURLOPT_RETURNTRANSFER – Ensures the response is returned as a string instead of outputting it directly.

2. Making a POST Request with cURL

A POST request is used to send data to a server, commonly for user registration or form submissions.

Example: Sending JSON Data to an API

$url = "https://jsonplaceholder.typicode.com/posts";  
$data = [  
    "title" => "Hello World",  
    "body" => "This is a test post.",  
    "userId" => 1  
];  

$ch = curl_init($url);  
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);  
curl_setopt($ch, CURLOPT_POST, true);  
curl_setopt($ch, CURLOPT_HTTPHEADER, ['Content-Type: application/json']);  
curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($data));  

$response = curl_exec($ch);  
curl_close($ch);  

echo $response;

✅ Key cURL Options:

• CURLOPT_POST – Enables the POST method.
• CURLOPT_POSTFIELDS – Sends the request payload.
• CURLOPT_HTTPHEADER – Sets the content type for JSON data.

3. Making a PUT Request with cURL

A PUT request updates an existing resource.

Example: Updating Data with PUT

$url = "https://jsonplaceholder.typicode.com/posts/1";  
$data = [  
    "title" => "Updated Title",  
    "body" => "Updated content.",  
    "userId" => 1  
];  

$ch = curl_init($url);  
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);  
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "PUT");  
curl_setopt($ch, CURLOPT_HTTPHEADER, ['Content-Type: application/json']);  
curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($data));  

$response = curl_exec($ch);  
curl_close($ch);  

echo $response;

✅ Key cURL Option: CURLOPT_CUSTOMREQUEST – Specifies HTTP methods like PUT, PATCH, or DELETE.

4. Making a PATCH Request with cURL

A PATCH request applies a partial update to an existing resource.

Example: Updating Only One Field with PATCH

$url = "https://jsonplaceholder.typicode.com/posts/1";  
$data = ["title" => "Patched Title"];  

$ch = curl_init($url);  
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);  
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "PATCH");  
curl_setopt($ch, CURLOPT_HTTPHEADER, ['Content-Type: application/json']);  
curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($data));  

$response = curl_exec($ch);  
curl_close($ch);  

echo $response;

✅ Use PATCH when updating specific fields instead of replacing the entire resource.

5. Making a DELETE Request with cURL

A DELETE request removes a resource from a server.

Example: Deleting a Resource

$url = "https://jsonplaceholder.typicode.com/posts/1";  

$ch = curl_init($url);  
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);  
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "DELETE");  

$response = curl_exec($ch);  
curl_close($ch);  

echo $response;

✅ Use DELETE to remove unwanted records from a database or API service.

6. Handling Authentication in cURL Requests

Many APIs require authentication using API keys or OAuth tokens.

Example: Using Bearer Token Authentication

$url = "https://api.example.com/user/profile";  

$ch = curl_init($url);  
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);  
curl_setopt($ch, CURLOPT_HTTPHEADER, [  
    'Authorization: Bearer YOUR_ACCESS_TOKEN',  
    'Content-Type: application/json'  
]);  

$response = curl_exec($ch);  
curl_close($ch);  

echo $response;

✅ Always use secure authentication methods when interacting with APIs.

7. Handling Timeouts in cURL Requests

To prevent requests from hanging indefinitely, set a timeout limit.

Example: Setting a Timeout

curl_setopt($ch, CURLOPT_TIMEOUT, 10);  // Timeout after 10 seconds

✅ Timeouts prevent delays in case of network issues.

8. Debugging and Error Handling in cURL

Check for errors in cURL requests to handle failures gracefully.

Example: Error Handling in cURL

$ch = curl_init($url);  
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);  

$response = curl_exec($ch);  

if ($response === false) {  
    echo "cURL Error: " . curl_error($ch);  
}  

curl_close($ch);

✅ Always check for errors when making HTTP requests to avoid silent failures.

Best Practices for Using cURL in PHP

✅ Use JSON for structured data exchange with APIs.
✅ Set timeouts to prevent indefinite waiting.
✅ Use error handling to catch and log failures.
✅ Use authentication headers for secured endpoints.
✅ Use CURLOPT_RETURNTRANSFER to return responses as strings instead of direct output.

Conclusion

cURL is an essential tool for making HTTP requests in PHP, allowing developers to interact with APIs, perform remote data fetching, and automate web services. By understanding GET, POST, PUT, PATCH, and DELETE requests, along with proper authentication, error handling, and optimization techniques, you can build robust and efficient API integrations.

By following best practices and handling responses correctly, you ensure secure and high-performance HTTP requests in your PHP applications. 🚀