How to Retrieve HTTP Response Headers in PHP Using get_headers()

In PHP development, obtaining the response headers of a web page or remote resource is often required. The get_headers() function provides a convenient way to fetch the headers of a target URL and returns them as an array.

Function Syntax

array get_headers(string $url, int $format = 0)

$url

is the target URL. $format is optional; when set to 0 (default) the function returns an associative array with both indexes and values, while 1 returns a simple indexed array.

Basic Usage Example

$url = "https://www.example.com";
$headers = get_headers($url);
// Print all response headers
print_r($headers);
// Print specific headers
echo $headers[0]; // First header (status line)
echo $headers[1]; // Second header (Date)

Typical output looks like:

Array (
    [0] => HTTP/1.1 200 OK
    [1] => Date: Thu, 19 Nov 2020 08:00:00 GMT
    [2] => Server: Apache/2.4.41
    [3] => Content-Type: text/html; charset=UTF-8
    [4] => Content-Length: 12345
    ...
)

Common Application Scenarios

Retrieve remote file information such as size and MIME type by examining the headers.

Check whether a remote file exists by inspecting the HTTP status code.

Use in web crawlers or network monitoring to decide further processing based on header data.

Note that get_headers() works only with the HTTP protocol; it cannot fetch headers for other protocols like FTP.

Conclusion

The get_headers() function is a practical tool for PHP developers, enabling easy access to HTTP response details such as status codes, dates, server information, and file metadata, thereby improving code usability and efficiency.