Guzzle: PHP HTTP client and framework for building RESTful web service clients

Github page here:

$client = new GuzzleHttp\Client();
$response = $client->get('');
$res = $client->get('', ['auth' =>  ['user', 'pass']]);
echo $res->getStatusCode();
// "200"
echo $res->getHeader('content-type');
// 'application/json; charset=utf8'
echo $res->getBody();
// {"type":"User"...'
// Outputs the JSON decoded data

// Send an asynchronous request.
$req = $client->createRequest('GET', '', ['future' => true]);
$client->send($req)->then(function ($response) {
    echo 'I completed! ' . $response;

Dropwizard: Java framework for developing ops-friendly, RESTful web services

Dropwizard logo

From the website:

Dropwizard pulls together stable, mature libraries from the Java ecosystem into a simple, light-weight package that lets you focus on getting things done.

Dropwizard has out-of-the-box support for sophisticated configuration, application metrics, logging, operational tools, and much more, allowing you and your team to ship a production-quality web service in the shortest time possible.

Also take a look at this page for a list of the components used in Dropwizard. In short, it uses:
Jetty for HTTP
Jersey for REST
Jackson for JSON
Metrics for metrics
– And a bunch of other tools for logging, templating, database access, et al.

Dropwizard logo

DHC (Dev HTTP Client) – Google Chrome extension to discover, manipulate, & test HTTP REST services

DHC logo

From the DHC Chrome Web Store page:

Easily construct custom HTTP requests, save them permanently, take advantage of variables and contexts.

DHC (aka Dev HTTP Client) is designed and developed by a developer for developers to make direct HTTP resource discovery, manipulation and testing more easily. Beside the main function, sending/receiving custom HTTP requests/responses, it allows permanently to save a request to a local repository for later reuse and moreover the request declaration can include variables that are context specific. With the use of contexts you can easily switch between various environments without modifying request declaration. (e.g. from a test environment to production)