diff --git a/src/Calendly.php b/src/Calendly.php
index 57af5a9..9d21a25 100644
--- a/src/Calendly.php
+++ b/src/Calendly.php
@@ -9,6 +9,7 @@
  * @method static Models\User getUser(string $uuid)
  * @method static Models\Organization getOrganization()
  * @method static Models\EventType[] getEventTypes(array $options)
+ * @method static array request(string $uri, string $method = "GET", array $params = [])
  */
 class Calendly
 {
diff --git a/src/CalendlyApi.php b/src/CalendlyApi.php
index 23a957c..de52594 100644
--- a/src/CalendlyApi.php
+++ b/src/CalendlyApi.php
@@ -8,6 +8,9 @@
 use LoBrs\Calendly\Exceptions\ApiErrorException;
 use LoBrs\Calendly\Exceptions\InternalServerErrorException;
 use LoBrs\Calendly\Exceptions\InvalidArgumentException;
+use LoBrs\Calendly\Exceptions\PermissionDeniedException;
+use LoBrs\Calendly\Exceptions\ResourceNotFoundException;
+use LoBrs\Calendly\Exceptions\UnauthenticatedException;
 use LoBrs\Calendly\Models\EventType;
 use LoBrs\Calendly\Models\Organization;
 use LoBrs\Calendly\Models\User;
@@ -15,18 +18,23 @@
 final class CalendlyApi
 {
     const API_URL = "https://api.calendly.com";
+
     private Client $client;
 
     /**
-     * @var string Token utilisateur Calendly
+     * @var string Calendly `user` or `organization` token
      */
     private string $token;
 
-    public function __construct(string $token) {
+    public function __construct(string $token, ?Client $httpClient = null) {
         $this->token = $token;
-        $this->client = new Client([
-            "base_uri" => self::API_URL,
-        ]);
+        if ($httpClient) {
+            $this->client = $httpClient;
+        } else {
+            $this->client = new Client([
+                "base_uri" => self::API_URL,
+            ]);
+        }
     }
 
     /**
@@ -49,22 +57,42 @@ public function request(string $uri, string $method = "GET", array $params = [])
         }
 
         $data = json_decode($response->getBody(), true);
-        if ($response->getStatusCode() > 299) {
+        $httpCode = $response->getStatusCode();
+        if ($httpCode > 299) {
             $message = $data['message'] ?? "Une erreur est survenue";
+            $details = $data['details'] ?? [];
             if (isset($data['title'])) {
+                // get exception class from title
                 $exceptionClassname = "LoBrs\\Calendly\\Exceptions\\" . str_replace(' ', '',
                         ucwords(str_replace(['-', '_'], ' ', $data['title']))) . "Exception";
                 if (class_exists($exceptionClassname)) {
-                    throw new $exceptionClassname($message, $data['details'] ?? []);
+                    throw new $exceptionClassname($message, $details);
                 }
             }
 
-            throw new ApiErrorException($message, $data['details'] ?? []);
+            if ($httpCode == 500) {
+                throw new InternalServerErrorException($message, $details);
+            }
+            if ($httpCode == 404) {
+                throw new ResourceNotFoundException($message, $details);
+            }
+            if ($httpCode == 403) {
+                throw new PermissionDeniedException($message, $details);
+            }
+            if ($httpCode == 401) {
+                throw new UnauthenticatedException($message, $details);
+            }
+
+            // Default API error exception
+            throw new ApiErrorException($message, $details);
         }
 
         return $data;
     }
 
+    /**
+     * @throws ApiErrorException|InvalidArgumentException
+     */
     public function me(): ?User {
         $response = $this->request("/users/me");
         if (isset($response["resource"])) {
@@ -73,6 +101,9 @@ public function me(): ?User {
         return null;
     }
 
+    /**
+     * @throws ApiErrorException|InvalidArgumentException
+     */
     public function getOrganization(?string $organization_uuid = null): ?Organization {
         if (empty($organization_uuid)) {
             return $this->me()->getCurrentOrganization();
@@ -81,6 +112,9 @@ public function getOrganization(?string $organization_uuid = null): ?Organizatio
         return Organization::get($organization_uuid);
     }
 
+    /**
+     * @throws ApiErrorException|InvalidArgumentException
+     */
     public function getUser(?string $uuid = null): ?User {
         if (empty($uuid)) {
             return $this->me();
@@ -89,6 +123,9 @@ public function getUser(?string $uuid = null): ?User {
         return User::get($uuid);
     }
 
+    /**
+     * @throws ApiErrorException|InvalidArgumentException
+     */
     public function getEventTypes(array $options): Utils\PaginatedList {
         return EventType::paginate($options);
     }
diff --git a/tests/CalendlyApiTest.php b/tests/CalendlyApiTest.php
new file mode 100644
index 0000000..71616c2
--- /dev/null
+++ b/tests/CalendlyApiTest.php
@@ -0,0 +1,52 @@
+<?php
+
+namespace LoBrs\Calendly\Test;
+
+use GuzzleHttp\Client;
+use GuzzleHttp\Handler\MockHandler;
+use GuzzleHttp\HandlerStack;
+use GuzzleHttp\Psr7\Response;
+use LoBrs\Calendly\CalendlyApi;
+use LoBrs\Calendly\Exceptions\InvalidArgumentException;
+use PHPUnit\Framework\TestCase;
+
+class CalendlyApiTest extends TestCase
+{
+
+    private CalendlyApi $api;
+    private MockHandler $mockHandler;
+
+    protected function setUp(): void {
+
+        $this->mockHandler = new MockHandler();
+        $httpClient = new Client([
+            'handler' => HandlerStack::create($this->mockHandler),
+        ]);
+
+        $this->api = new CalendlyApi("secret", $httpClient);
+    }
+
+    public function testOkResponse() {
+
+        $this->mockHandler->append(new Response(200, [
+            'content-type' => 'application/json; charset=utf-8',
+        ], '{"foo": "bar"}'));
+
+        $response = $this->api->request("/foo");
+        $this->assertEquals("bar", $response["foo"]);
+    }
+
+    public function testExceptionResponse() {
+
+        $this->expectException(InvalidArgumentException::class);
+
+        $this->mockHandler->append(new Response(400, [
+            'content-type' => 'application/json; charset=utf-8',
+        ], '{"title": "Invalid Argument", "message": "There is an error", "details": [{"foo":"bar"}]}'));
+
+        $this->api->request("/foo");
+        $this->assertIsArray($this->getExpectedException()->getDetails());
+        $this->assertEquals("There is an error", $this->getExpectedException()->getMessage());
+    }
+
+}
\ No newline at end of file