['examplekey' => 'secret-key-here'], 'algorithm' => 'hmac-sha256', 'headers' => ['(request-target)', 'date'], ]); $handlerStack = GuzzleHttpSignatures::defaultHandlerFromContext($context); $client = new Client(['handler' => $handlerStack]); // The below will now send a signed request to: http://example.org/path?query=123 $response = $client->get("http://www.example.com/path?query=123", ['headers' => ['date' => 'today']]);