Does Guzzle require cURL?

No. Guzzle can use any HTTP handler to send requests. This means that Guzzle can be used with cURL, PHP's stream wrapper, sockets, and non-blocking libraries like React. You just need to configure an HTTP handler to use a different method of sending requests.


Guzzle has historically only utilized cURL to send HTTP requests. cURL is an amazing HTTP client (arguably the best), and Guzzle will continue to use it by default when it is available. It is rare, but some developers don't have cURL installed on their systems or run into version specific issues. By allowing swappable HTTP handlers, Guzzle is now much more customizable and able to adapt to fit the needs of more developers.

Can Guzzle send asynchronous requests?

Yes. You can use the requestAsync, sendAsync, getAsync, headAsync, putAsync, postAsync, deleteAsync, and patchAsync methods of a client to send an asynchronous request. The client will return a GuzzleHttp\Promise\PromiseInterface object. You can chain then functions off of the promise.

$promise = $client->requestAsync('GET', 'http://httpbin.org/get');
$promise->then(function ($response) {
    echo 'Got a response! ' . $response->getStatusCode();

You can force an asynchronous response to complete using the wait() method of the returned promise.

$promise = $client->requestAsync('GET', 'http://httpbin.org/get');
$response = $promise->wait();

How can I add custom cURL options?

cURL offer a huge number of customizable options. While Guzzle normalizes many of these options across different handlers, there are times when you need to set custom cURL options. This can be accomplished by passing an associative array of cURL settings in the curl key of a request.

For example, let's say you need to customize the outgoing network interface used with a client.

$client->request('GET', '/', [
    'curl' => [
        CURLOPT_INTERFACE => 'xxx.xxx.xxx.xxx'

How can I add custom stream context options?

You can pass custom stream context options using the stream_context key of the request option. The stream_context array is an associative array where each key is a PHP transport, and each value is an associative array of transport options.

For example, let's say you need to customize the outgoing network interface used with a client and allow self-signed certificates.

$client->request('GET', '/', [
    'stream' => true,
    'stream_context' => [
        'ssl' => [
            'allow_self_signed' => true
        'socket' => [
            'bindto' => 'xxx.xxx.xxx.xxx'

Why am I getting an SSL verification error?

You need to specify the path on disk to the CA bundle used by Guzzle for verifying the peer certificate. See verify.

What is this Maximum function nesting error?

Maximum function nesting level of '100' reached, aborting

You could run into this error if you have the XDebug extension installed and you execute a lot of requests in callbacks. This error message comes specifically from the XDebug extension. PHP itself does not have a function nesting limit. Change this setting in your php.ini to increase the limit:

xdebug.max_nesting_level = 1000

Why am I getting a 417 error response?

This can occur for a number of reasons, but if you are sending PUT, POST, or PATCH requests with an Expect: 100-Continue header, a server that does not support this header will return a 417 response. You can work around this by setting the expect request option to false:

$client = new GuzzleHttp\Client();

// Disable the expect header on a single request
$response = $client->request('PUT', '/', ['expect' => false]);

// Disable the expect header on all client requests
$client = new GuzzleHttp\Client(['expect' => false]);

How can I track a redirected requests?

You can enable tracking of redirected URIs and status codes via the track_redirects option. Each redirected URI and status code will be stored in the X-Guzzle-Redirect-History and the X-Guzzle-Redirect-Status-History header respectively.

The initial request's URI and the final status code will be excluded from the results. With this in mind you should be able to easily track a request's full redirect path.

For example, let's say you need to track redirects and provide both results together in a single report:

// First you configure Guzzle with redirect tracking and make a request
$client = new Client([
    RequestOptions::ALLOW_REDIRECTS => [
        'max'             => 10,        // allow at most 10 redirects.
        'strict'          => true,      // use "strict" RFC compliant redirects.
        'referer'         => true,      // add a Referer header
        'track_redirects' => true,
$initialRequest = '/redirect/3'; // Store the request URI for later use
$response = $client->request('GET', $initialRequest); // Make your request

// Retrieve both Redirect History headers
$redirectUriHistory = $response->getHeader('X-Guzzle-Redirect-History'); // retrieve Redirect URI history
$redirectCodeHistory = $response->getHeader('X-Guzzle-Redirect-Status-History'); // retrieve Redirect HTTP Status history

// Add the initial URI requested to the (beginning of) URI history
array_unshift($redirectUriHistory, $initialRequest);

// Add the final HTTP status code to the end of HTTP response history
array_push($redirectCodeHistory, $response->getStatusCode());

// (Optional) Combine the items of each array into a single result set
$fullRedirectReport = [];
foreach ($redirectUriHistory as $key => $value) {
    $fullRedirectReport[$key] = ['location' => $value, 'code' => $redirectCodeHistory[$key]];
echo json_encode($fullRedirectReport);