diff --git a/app/Client/Client.php b/app/Client/Client.php
index 0aef2aa..6380539 100644
--- a/app/Client/Client.php
+++ b/app/Client/Client.php
@@ -197,6 +197,14 @@ class Client
 
     protected function attachCommonConnectionListeners(ControlConnection $connection, Deferred $deferred)
     {
+        $connection->on('info', function ($data) {
+            $this->logger->info($data->message);
+        });
+
+        $connection->on('error', function ($data) {
+            $this->logger->error($data->message);
+        });
+
         $connection->on('authenticationFailed', function ($data) use ($deferred) {
             $this->logger->error($data->message);
 
diff --git a/app/Contracts/SubdomainRepository.php b/app/Contracts/SubdomainRepository.php
new file mode 100644
index 0000000..a32158b
--- /dev/null
+++ b/app/Contracts/SubdomainRepository.php
@@ -0,0 +1,22 @@
+<?php
+
+namespace App\Contracts;
+
+use React\Promise\PromiseInterface;
+
+interface SubdomainRepository
+{
+    public function getSubdomains(): PromiseInterface;
+
+    public function getSubdomainById($id): PromiseInterface;
+
+    public function getSubdomainByName(string $name): PromiseInterface;
+
+    public function getSubdomainsByUserId($id): PromiseInterface;
+
+    public function getSubdomainsByUserIdAndName($id, $name): PromiseInterface;
+
+    public function deleteSubdomainForUserId($userId, $subdomainId): PromiseInterface;
+
+    public function storeSubdomain(array $data): PromiseInterface;
+}
diff --git a/app/Server/Factory.php b/app/Server/Factory.php
index 349de6b..9f7e728 100644
--- a/app/Server/Factory.php
+++ b/app/Server/Factory.php
@@ -4,10 +4,12 @@ namespace App\Server;
 
 use App\Contracts\ConnectionManager as ConnectionManagerContract;
 use App\Contracts\SubdomainGenerator;
+use App\Contracts\SubdomainRepository;
 use App\Contracts\UserRepository;
 use App\Http\RouteGenerator;
 use App\Http\Server as HttpServer;
 use App\Server\Connections\ConnectionManager;
+use App\Server\Http\Controllers\Admin\DeleteSubdomainController;
 use App\Server\Http\Controllers\Admin\DeleteUsersController;
 use App\Server\Http\Controllers\Admin\DisconnectSiteController;
 use App\Server\Http\Controllers\Admin\DisconnectTcpConnectionController;
@@ -22,6 +24,7 @@ use App\Server\Http\Controllers\Admin\ListUsersController;
 use App\Server\Http\Controllers\Admin\RedirectToUsersController;
 use App\Server\Http\Controllers\Admin\ShowSettingsController;
 use App\Server\Http\Controllers\Admin\StoreSettingsController;
+use App\Server\Http\Controllers\Admin\StoreSubdomainController;
 use App\Server\Http\Controllers\Admin\StoreUsersController;
 use App\Server\Http\Controllers\ControlMessageController;
 use App\Server\Http\Controllers\TunnelMessageController;
@@ -130,6 +133,8 @@ class Factory
         $this->router->get('/api/users', GetUsersController::class, $adminCondition);
         $this->router->post('/api/users', StoreUsersController::class, $adminCondition);
         $this->router->get('/api/users/{id}', GetUserDetailsController::class, $adminCondition);
+        $this->router->post('/api/subdomains', StoreSubdomainController::class, $adminCondition);
+        $this->router->delete('/api/subdomains/{subdomain}', DeleteSubdomainController::class, $adminCondition);
         $this->router->delete('/api/users/{id}', DeleteUsersController::class, $adminCondition);
         $this->router->get('/api/sites', GetSitesController::class, $adminCondition);
         $this->router->delete('/api/sites/{id}', DisconnectSiteController::class, $adminCondition);
@@ -171,6 +176,7 @@ class Factory
         $this->bindConfiguration()
             ->bindSubdomainGenerator()
             ->bindUserRepository()
+            ->bindSubdomainRepository()
             ->bindDatabase()
             ->ensureDatabaseIsInitialized()
             ->bindConnectionManager()
@@ -207,6 +213,15 @@ class Factory
         return $this;
     }
 
+    protected function bindSubdomainRepository()
+    {
+        app()->singleton(SubdomainRepository::class, function () {
+            return app(config('expose.admin.subdomain_repository'));
+        });
+
+        return $this;
+    }
+
     protected function bindDatabase()
     {
         app()->singleton(DatabaseInterface::class, function () {
diff --git a/app/Server/Http/Controllers/Admin/DeleteSubdomainController.php b/app/Server/Http/Controllers/Admin/DeleteSubdomainController.php
new file mode 100644
index 0000000..9cad085
--- /dev/null
+++ b/app/Server/Http/Controllers/Admin/DeleteSubdomainController.php
@@ -0,0 +1,44 @@
+<?php
+
+namespace App\Server\Http\Controllers\Admin;
+
+use App\Contracts\SubdomainRepository;
+use App\Contracts\UserRepository;
+use Illuminate\Http\Request;
+use Ratchet\ConnectionInterface;
+
+class DeleteSubdomainController extends AdminController
+{
+    protected $keepConnectionOpen = true;
+
+    /** @var SubdomainRepository */
+    protected $subdomainRepository;
+
+    /** @var UserRepository */
+    protected $userRepository;
+
+    public function __construct(UserRepository $userRepository, SubdomainRepository $subdomainRepository)
+    {
+        $this->userRepository = $userRepository;
+        $this->subdomainRepository = $subdomainRepository;
+    }
+
+    public function handle(Request $request, ConnectionInterface $httpConnection)
+    {
+        $this->userRepository->getUserByToken($request->get('auth_token', ''))
+            ->then(function ($user) use ($request, $httpConnection) {
+                if (is_null($user)) {
+                    $httpConnection->send(respond_json(['error' => 'The user does not exist'], 404));
+                    $httpConnection->close();
+
+                    return;
+                }
+
+                $this->subdomainRepository->deleteSubdomainForUserId($user['id'], $request->get('subdomain'))
+                    ->then(function ($deleted) use ($httpConnection) {
+                        $httpConnection->send(respond_json(['deleted' => $deleted], 200));
+                        $httpConnection->close();
+                    });
+            });
+    }
+}
diff --git a/app/Server/Http/Controllers/Admin/GetUserDetailsController.php b/app/Server/Http/Controllers/Admin/GetUserDetailsController.php
index 2cb3a52..6fe8b0d 100644
--- a/app/Server/Http/Controllers/Admin/GetUserDetailsController.php
+++ b/app/Server/Http/Controllers/Admin/GetUserDetailsController.php
@@ -2,6 +2,7 @@
 
 namespace App\Server\Http\Controllers\Admin;
 
+use App\Contracts\SubdomainRepository;
 use App\Contracts\UserRepository;
 use Illuminate\Http\Request;
 use Ratchet\ConnectionInterface;
@@ -13,21 +14,31 @@ class GetUserDetailsController extends AdminController
     /** @var UserRepository */
     protected $userRepository;
 
-    public function __construct(UserRepository $userRepository)
+    /** @var SubdomainRepository */
+    protected $subdomainRepository;
+
+    public function __construct(UserRepository $userRepository, SubdomainRepository $subdomainRepository)
     {
         $this->userRepository = $userRepository;
+        $this->subdomainRepository = $subdomainRepository;
     }
 
     public function handle(Request $request, ConnectionInterface $httpConnection)
     {
         $this->userRepository
             ->getUserById($request->get('id'))
-            ->then(function ($user) use ($httpConnection) {
-                $httpConnection->send(
-                    respond_json(['user' => $user])
-                );
+            ->then(function ($user) use ($httpConnection, $request) {
+                $this->subdomainRepository->getSubdomainsByUserId($request->get('id'))
+                    ->then(function ($subdomains) use ($httpConnection, $user) {
+                        $httpConnection->send(
+                            respond_json([
+                                'user' => $user,
+                                'subdomains' => $subdomains,
+                            ])
+                        );
 
-                $httpConnection->close();
+                        $httpConnection->close();
+                    });
             });
     }
 }
diff --git a/app/Server/Http/Controllers/Admin/StoreSubdomainController.php b/app/Server/Http/Controllers/Admin/StoreSubdomainController.php
new file mode 100644
index 0000000..b216b96
--- /dev/null
+++ b/app/Server/Http/Controllers/Admin/StoreSubdomainController.php
@@ -0,0 +1,77 @@
+<?php
+
+namespace App\Server\Http\Controllers\Admin;
+
+use App\Contracts\SubdomainRepository;
+use App\Contracts\UserRepository;
+use Illuminate\Http\Request;
+use Illuminate\Support\Facades\Validator;
+use Ratchet\ConnectionInterface;
+
+class StoreSubdomainController extends AdminController
+{
+    protected $keepConnectionOpen = true;
+
+    /** @var SubdomainRepository */
+    protected $subdomainRepository;
+
+    /** @var UserRepository */
+    protected $userRepository;
+
+    public function __construct(UserRepository $userRepository, SubdomainRepository $subdomainRepository)
+    {
+        $this->userRepository = $userRepository;
+        $this->subdomainRepository = $subdomainRepository;
+    }
+
+    public function handle(Request $request, ConnectionInterface $httpConnection)
+    {
+        $validator = Validator::make($request->all(), [
+            'subdomain' => 'required',
+        ], [
+            'required' => 'The :attribute field is required.',
+        ]);
+
+        if ($validator->fails()) {
+            $httpConnection->send(respond_json(['errors' => $validator->getMessageBag()], 401));
+            $httpConnection->close();
+
+            return;
+        }
+
+        $this->userRepository->getUserByToken($request->get('auth_token', ''))
+            ->then(function ($user) use ($httpConnection, $request) {
+                if (is_null($user)) {
+                    $httpConnection->send(respond_json(['error' => 'The user does not exist'], 404));
+                    $httpConnection->close();
+
+                    return;
+                }
+
+                if ($user['can_specify_subdomains'] === 0) {
+                    $httpConnection->send(respond_json(['error' => 'The user is not allowed to reserve subdomains.'], 401));
+                    $httpConnection->close();
+
+                    return;
+                }
+
+                $insertData = [
+                    'user_id' => $user['id'],
+                    'subdomain' => $request->get('subdomain'),
+                ];
+
+                $this->subdomainRepository
+                    ->storeSubdomain($insertData)
+                    ->then(function ($subdomain) use ($httpConnection) {
+                        if (is_null($subdomain)) {
+                            $httpConnection->send(respond_json(['error' => 'The subdomain is already taken.'], 422));
+                            $httpConnection->close();
+
+                            return;
+                        }
+                        $httpConnection->send(respond_json(['subdomain' => $subdomain], 200));
+                        $httpConnection->close();
+                    });
+            });
+    }
+}
diff --git a/app/Server/Http/Controllers/ControlMessageController.php b/app/Server/Http/Controllers/ControlMessageController.php
index d1bccc2..dc8b34b 100644
--- a/app/Server/Http/Controllers/ControlMessageController.php
+++ b/app/Server/Http/Controllers/ControlMessageController.php
@@ -3,6 +3,7 @@
 namespace App\Server\Http\Controllers;
 
 use App\Contracts\ConnectionManager;
+use App\Contracts\SubdomainRepository;
 use App\Contracts\UserRepository;
 use App\Http\QueryParameters;
 use App\Server\Exceptions\NoFreePortAvailable;
@@ -20,10 +21,14 @@ class ControlMessageController implements MessageComponentInterface
     /** @var UserRepository */
     protected $userRepository;
 
-    public function __construct(ConnectionManager $connectionManager, UserRepository $userRepository)
+    /** @var SubdomainRepository */
+    protected $subdomainRepository;
+
+    public function __construct(ConnectionManager $connectionManager, UserRepository $userRepository, SubdomainRepository $subdomainRepository)
     {
         $this->connectionManager = $connectionManager;
         $this->userRepository = $userRepository;
+        $this->subdomainRepository = $subdomainRepository;
     }
 
     /**
@@ -100,22 +105,26 @@ class ControlMessageController implements MessageComponentInterface
 
     protected function handleHttpConnection(ConnectionInterface $connection, $data, $user = null)
     {
-        if (! $this->hasValidSubdomain($connection, $data->subdomain, $user)) {
-            return;
-        }
+        $this->hasValidSubdomain($connection, $data->subdomain, $user)->then(function ($subdomain) use ($data, $connection) {
+            if ($subdomain === false) {
+                return;
+            }
 
-        $connectionInfo = $this->connectionManager->storeConnection($data->host, $data->subdomain, $connection);
+            $data->subdomain = $subdomain;
 
-        $this->connectionManager->limitConnectionLength($connectionInfo, config('expose.admin.maximum_connection_length'));
+            $connectionInfo = $this->connectionManager->storeConnection($data->host, $data->subdomain, $connection);
 
-        $connection->send(json_encode([
-            'event' => 'authenticated',
-            'data' => [
-                'message' => config('expose.admin.messages.message_of_the_day'),
-                'subdomain' => $connectionInfo->subdomain,
-                'client_id' => $connectionInfo->client_id,
-            ],
-        ]));
+            $this->connectionManager->limitConnectionLength($connectionInfo, config('expose.admin.maximum_connection_length'));
+
+            $connection->send(json_encode([
+                'event' => 'authenticated',
+                'data' => [
+                    'message' => config('expose.admin.messages.message_of_the_day'),
+                    'subdomain' => $connectionInfo->subdomain,
+                    'client_id' => $connectionInfo->client_id,
+                ],
+            ]));
+        });
     }
 
     protected function handleTcpConnection(ConnectionInterface $connection, $data, $user = null)
@@ -203,39 +212,65 @@ class ControlMessageController implements MessageComponentInterface
         return $deferred->promise();
     }
 
-    protected function hasValidSubdomain(ConnectionInterface $connection, ?string $subdomain, ?array $user): bool
+    protected function hasValidSubdomain(ConnectionInterface $connection, ?string $subdomain, ?array $user): PromiseInterface
     {
+        /**
+         * Check if the user can specify a custom subdomain in the first place.
+         */
         if (! is_null($user) && $user['can_specify_subdomains'] === 0 && ! is_null($subdomain)) {
             $connection->send(json_encode([
-                'event' => 'subdomainTaken',
+                'event' => 'info',
                 'data' => [
-                    'message' => config('expose.admin.messages.custom_subdomain_unauthorized'),
+                    'message' => config('expose.admin.messages.custom_subdomain_unauthorized').PHP_EOL,
                 ],
             ]));
-            $connection->close();
 
-            return false;
+            return \React\Promise\resolve(null);
         }
 
+        /**
+         * Check if the given subdomain is reserved for a different user.
+         */
         if (! is_null($subdomain)) {
-            $controlConnection = $this->connectionManager->findControlConnectionForSubdomain($subdomain);
-            if (! is_null($controlConnection) || $subdomain === config('expose.admin.subdomain')) {
-                $message = config('expose.admin.messages.subdomain_taken');
-                $message = str_replace(':subdomain', $subdomain, $message);
+            return $this->subdomainRepository->getSubdomainByName($subdomain)
+                ->then(function ($foundSubdomain) use ($connection, $subdomain, $user) {
+                    if (! is_null($foundSubdomain) && ! is_null($user) && $foundSubdomain['user_id'] !== $user['id']) {
+                        $message = config('expose.admin.messages.subdomain_reserved');
+                        $message = str_replace(':subdomain', $subdomain, $message);
 
-                $connection->send(json_encode([
-                    'event' => 'subdomainTaken',
-                    'data' => [
-                        'message' => $message,
-                    ],
-                ]));
-                $connection->close();
+                        $connection->send(json_encode([
+                            'event' => 'subdomainTaken',
+                            'data' => [
+                                'message' => $message,
+                            ],
+                        ]));
+                        $connection->close();
 
-                return false;
-            }
+                        return \React\Promise\resolve(false);
+                    }
+
+                    $controlConnection = $this->connectionManager->findControlConnectionForSubdomain($subdomain);
+
+                    if (! is_null($controlConnection) || $subdomain === config('expose.admin.subdomain')) {
+                        $message = config('expose.admin.messages.subdomain_taken');
+                        $message = str_replace(':subdomain', $subdomain, $message);
+
+                        $connection->send(json_encode([
+                            'event' => 'subdomainTaken',
+                            'data' => [
+                                'message' => $message,
+                            ],
+                        ]));
+                        $connection->close();
+
+                        return \React\Promise\resolve(false);
+                    }
+
+                    return \React\Promise\resolve($subdomain);
+                });
         }
 
-        return true;
+        return \React\Promise\resolve($subdomain);
     }
 
     protected function canShareTcpPorts(ConnectionInterface $connection, $data, $user)
diff --git a/app/Server/SubdomainRepository/DatabaseSubdomainRepository.php b/app/Server/SubdomainRepository/DatabaseSubdomainRepository.php
new file mode 100644
index 0000000..b6b0de8
--- /dev/null
+++ b/app/Server/SubdomainRepository/DatabaseSubdomainRepository.php
@@ -0,0 +1,132 @@
+<?php
+
+namespace App\Server\SubdomainRepository;
+
+use App\Contracts\SubdomainRepository;
+use Clue\React\SQLite\DatabaseInterface;
+use Clue\React\SQLite\Result;
+use React\Promise\Deferred;
+use React\Promise\PromiseInterface;
+
+class DatabaseSubdomainRepository implements SubdomainRepository
+{
+    /** @var DatabaseInterface */
+    protected $database;
+
+    public function __construct(DatabaseInterface $database)
+    {
+        $this->database = $database;
+    }
+
+    public function getSubdomains(): PromiseInterface
+    {
+        $deferred = new Deferred();
+
+        $this->database
+            ->query('SELECT * FROM subdomains ORDER by created_at DESC')
+            ->then(function (Result $result) use ($deferred) {
+                $deferred->resolve($result->rows);
+            });
+
+        return $deferred->promise();
+    }
+
+    public function getSubdomainById($id): PromiseInterface
+    {
+        $deferred = new Deferred();
+
+        $this->database
+            ->query('SELECT * FROM subdomains WHERE id = :id', ['id' => $id])
+            ->then(function (Result $result) use ($deferred) {
+                $deferred->resolve($result->rows[0] ?? null);
+            });
+
+        return $deferred->promise();
+    }
+
+    public function getSubdomainByName(string $name): PromiseInterface
+    {
+        $deferred = new Deferred();
+
+        $this->database
+            ->query('SELECT * FROM subdomains WHERE subdomain = :name', ['name' => $name])
+            ->then(function (Result $result) use ($deferred) {
+                $deferred->resolve($result->rows[0] ?? null);
+            });
+
+        return $deferred->promise();
+    }
+
+    public function getSubdomainsByUserId($id): PromiseInterface
+    {
+        $deferred = new Deferred();
+
+        $this->database
+            ->query('SELECT * FROM subdomains WHERE user_id = :user_id ORDER by created_at DESC', [
+                'user_id' => $id,
+            ])
+            ->then(function (Result $result) use ($deferred) {
+                $deferred->resolve($result->rows);
+            });
+
+        return $deferred->promise();
+    }
+
+    public function storeSubdomain(array $data): PromiseInterface
+    {
+        $deferred = new Deferred();
+
+        $this->getSubdomainByName($data['subdomain'])
+            ->then(function ($registeredSubdomain) use ($data, $deferred) {
+                if (! is_null($registeredSubdomain)) {
+                    $deferred->resolve(null);
+
+                    return;
+                }
+
+                $this->database->query("
+                    INSERT INTO subdomains (user_id, subdomain, created_at)
+                    VALUES (:user_id, :subdomain, DATETIME('now'))
+                ", $data)
+                    ->then(function (Result $result) use ($deferred) {
+                        $this->database->query('SELECT * FROM subdomains WHERE id = :id', ['id' => $result->insertId])
+                            ->then(function (Result $result) use ($deferred) {
+                                $deferred->resolve($result->rows[0]);
+                            });
+                    });
+            });
+
+        return $deferred->promise();
+    }
+
+    public function getSubdomainsByUserIdAndName($id, $name): PromiseInterface
+    {
+        $deferred = new Deferred();
+
+        $this->database
+            ->query('SELECT * FROM subdomains WHERE user_id = :user_id AND subdomain = :name ORDER by created_at DESC', [
+                'user_id' => $id,
+                'name' => $name,
+            ])
+            ->then(function (Result $result) use ($deferred) {
+                $deferred->resolve($result->rows);
+            });
+
+        return $deferred->promise();
+    }
+
+    public function deleteSubdomainForUserId($userId, $subdomainId): PromiseInterface
+    {
+        $deferred = new Deferred();
+
+        $this->database->query('DELETE FROM subdomains WHERE id = :id AND user_id = :user_id', [
+            'id' => $subdomainId,
+            'user_id' => $userId,
+        ])
+            ->then(function (Result $result) use ($deferred) {
+                $deferred->resolve($result);
+            });
+
+        return $deferred->promise();
+    }
+}
diff --git a/config/expose.php b/config/expose.php
index a48fa6f..f1a754f 100644
--- a/config/expose.php
+++ b/config/expose.php
@@ -232,6 +232,8 @@ return [
         */
         'user_repository' => \App\Server\UserRepository\DatabaseUserRepository::class,
 
+        'subdomain_repository' => \App\Server\SubdomainRepository\DatabaseSubdomainRepository::class,
+
         /*
         |--------------------------------------------------------------------------
         | Messages
@@ -249,7 +251,7 @@ return [
 
             'subdomain_taken' => 'The chosen subdomain :subdomain is already taken. Please choose a different subdomain.',
 
-            'custom_subdomain_unauthorized' => 'You are not allowed to specify custom subdomains. Please upgrade to Expose Pro.',
+            'custom_subdomain_unauthorized' => 'You are not allowed to specify custom subdomains. Please upgrade to Expose Pro. Assigning a random subdomain instead.',
 
             'no_free_tcp_port_available' => 'There are no free TCP ports available on this server. Please try again later.',
         ],
diff --git a/database/migrations/04_create_subdomains_table.sql b/database/migrations/04_create_subdomains_table.sql
new file mode 100644
index 0000000..adedb65
--- /dev/null
+++ b/database/migrations/04_create_subdomains_table.sql
@@ -0,0 +1,7 @@
+CREATE TABLE IF NOT EXISTS subdomains (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    user_id INTEGER NOT NULL,
+    subdomain STRING NOT NULL,
+    created_at DATETIME,
+    updated_at DATETIME
+)
diff --git a/tests/Feature/Server/ApiTest.php b/tests/Feature/Server/ApiTest.php
index 620a91e..3bdde90 100644
--- a/tests/Feature/Server/ApiTest.php
+++ b/tests/Feature/Server/ApiTest.php
@@ -5,6 +5,7 @@ namespace Tests\Feature\Server;
 use App\Contracts\ConnectionManager;
 use App\Server\Factory;
 use Clue\React\Buzz\Browser;
+use Clue\React\Buzz\Message\ResponseException;
 use GuzzleHttp\Psr7\Response;
 use Nyholm\Psr7\Request;
 use Ratchet\Server\IoConnection;
@@ -65,10 +66,10 @@ class ApiTest extends TestCase
     }
 
     /** @test */
-    public function it_can_get_user_details()
+    public function it_does_not_allow_subdomain_reservation_for_users_without_the_right_flag()
     {
         /** @var Response $response */
-        $this->await($this->browser->post('http://127.0.0.1:8080/api/users', [
+        $response = $this->await($this->browser->post('http://127.0.0.1:8080/api/users', [
             'Host' => 'expose.localhost',
             'Authorization' => base64_encode('username:secret'),
             'Content-Type' => 'application/json',
@@ -76,6 +77,72 @@ class ApiTest extends TestCase
             'name' => 'Marcel',
         ])));
 
+        $user = json_decode($response->getBody()->getContents())->user;
+
+        $this->expectException(ResponseException::class);
+        $this->expectExceptionMessage('HTTP status code 401');
+
+        $this->await($this->browser->post('http://127.0.0.1:8080/api/subdomains', [
+            'Host' => 'expose.localhost',
+            'Authorization' => base64_encode('username:secret'),
+            'Content-Type' => 'application/json',
+        ], json_encode([
+            'auth_token' => $user->auth_token,
+            'subdomain' => 'reserved',
+        ])));
+    }
+
+    /** @test */
+    public function it_allows_subdomain_reservation_for_users_with_the_right_flag()
+    {
+        /** @var Response $response */
+        $response = $this->await($this->browser->post('http://127.0.0.1:8080/api/users', [
+            'Host' => 'expose.localhost',
+            'Authorization' => base64_encode('username:secret'),
+            'Content-Type' => 'application/json',
+        ], json_encode([
+            'name' => 'Marcel',
+            'can_specify_subdomains' => 1,
+        ])));
+
+        $user = json_decode($response->getBody()->getContents())->user;
+
+        $response = $this->await($this->browser->post('http://127.0.0.1:8080/api/subdomains', [
+            'Host' => 'expose.localhost',
+            'Authorization' => base64_encode('username:secret'),
+            'Content-Type' => 'application/json',
+        ], json_encode([
+            'auth_token' => $user->auth_token,
+            'subdomain' => 'reserved',
+        ])));
+
+        $this->assertSame(200, $response->getStatusCode());
+    }
+
+    /** @test */
+    public function it_can_get_user_details()
+    {
+        /** @var Response $response */
+        $response = $this->await($this->browser->post('http://127.0.0.1:8080/api/users', [
+            'Host' => 'expose.localhost',
+            'Authorization' => base64_encode('username:secret'),
+            'Content-Type' => 'application/json',
+        ], json_encode([
+            'name' => 'Marcel',
+            'can_specify_subdomains' => 1,
+        ])));
+
+        $user = json_decode($response->getBody()->getContents())->user;
+
+        $this->await($this->browser->post('http://127.0.0.1:8080/api/subdomains', [
+            'Host' => 'expose.localhost',
+            'Authorization' => base64_encode('username:secret'),
+            'Content-Type' => 'application/json',
+        ], json_encode([
+            'auth_token' => $user->auth_token,
+            'subdomain' => 'reserved',
+        ])));
+
         /** @var Response $response */
         $response = $this->await($this->browser->get('http://127.0.0.1:8080/api/users/1', [
             'Host' => 'expose.localhost',
@@ -85,10 +152,117 @@ class ApiTest extends TestCase
 
         $body = json_decode($response->getBody()->getContents());
         $user = $body->user;
+        $subdomains = $body->subdomains;
 
         $this->assertSame('Marcel', $user->name);
         $this->assertSame([], $user->sites);
         $this->assertSame([], $user->tcp_connections);
+
+        $this->assertCount(1, $subdomains);
+    }
+
+    /** @test */
+    public function it_can_delete_subdomains()
+    {
+        /** @var Response $response */
+        $response = $this->await($this->browser->post('http://127.0.0.1:8080/api/users', [
+            'Host' => 'expose.localhost',
+            'Authorization' => base64_encode('username:secret'),
+            'Content-Type' => 'application/json',
+        ], json_encode([
+            'name' => 'Marcel',
+            'can_specify_subdomains' => 1,
+        ])));
+
+        $user = json_decode($response->getBody()->getContents())->user;
+
+        $response = $this->await($this->browser->post('http://127.0.0.1:8080/api/subdomains', [
+            'Host' => 'expose.localhost',
+            'Authorization' => base64_encode('username:secret'),
+            'Content-Type' => 'application/json',
+        ], json_encode([
+            'subdomain' => 'reserved',
+            'auth_token' => $user->auth_token,
+        ])));
+
+        $this->await($this->browser->delete('http://127.0.0.1:8080/api/subdomains/1', [
+            'Host' => 'expose.localhost',
+            'Authorization' => base64_encode('username:secret'),
+            'Content-Type' => 'application/json',
+        ], json_encode([
+            'auth_token' => $user->auth_token,
+        ])));
+
+        /** @var Response $response */
+        $response = $this->await($this->browser->get('http://127.0.0.1:8080/api/users/1', [
+            'Host' => 'expose.localhost',
+            'Authorization' => base64_encode('username:secret'),
+            'Content-Type' => 'application/json',
+        ]));
+
+        $body = json_decode($response->getBody()->getContents());
+        $subdomains = $body->subdomains;
+
+        $this->assertCount(0, $subdomains);
+    }
+
+    /** @test */
+    public function it_can_not_reserve_an_already_reserved_subdomain()
+    {
+        /** @var Response $response */
+        $response = $this->await($this->browser->post('http://127.0.0.1:8080/api/users', [
+            'Host' => 'expose.localhost',
+            'Authorization' => base64_encode('username:secret'),
+            'Content-Type' => 'application/json',
+        ], json_encode([
+            'name' => 'Marcel',
+            'can_specify_subdomains' => 1,
+        ])));
+
+        $user = json_decode($response->getBody()->getContents())->user;
+
+        $this->await($this->browser->post('http://127.0.0.1:8080/api/subdomains', [
+            'Host' => 'expose.localhost',
+            'Authorization' => base64_encode('username:secret'),
+            'Content-Type' => 'application/json',
+        ], json_encode([
+            'subdomain' => 'reserved',
+            'auth_token' => $user->auth_token,
+        ])));
+
+        $response = $this->await($this->browser->post('http://127.0.0.1:8080/api/users', [
+            'Host' => 'expose.localhost',
+            'Authorization' => base64_encode('username:secret'),
+            'Content-Type' => 'application/json',
+        ], json_encode([
+            'name' => 'Sebastian',
+            'can_specify_subdomains' => 1,
+        ])));
+
+        $user = json_decode($response->getBody()->getContents())->user;
+
+        $this->expectException(ResponseException::class);
+        $this->expectExceptionMessage('HTTP status code 422');
+
+        $this->await($this->browser->post('http://127.0.0.1:8080/api/subdomains', [
+            'Host' => 'expose.localhost',
+            'Authorization' => base64_encode('username:secret'),
+            'Content-Type' => 'application/json',
+        ], json_encode([
+            'subdomain' => 'reserved',
+            'auth_token' => $user->auth_token,
+        ])));
+
+        $response = $this->await($this->browser->get('http://127.0.0.1:8080/api/users/2', [
+            'Host' => 'expose.localhost',
+            'Authorization' => base64_encode('username:secret'),
+            'Content-Type' => 'application/json',
+        ]));
+
+        $body = json_decode($response->getBody()->getContents());
+        $subdomains = $body->subdomains;
+
+        $this->assertCount(0, $subdomains);
     }
 
     /** @test */
diff --git a/tests/Feature/Server/TunnelTest.php b/tests/Feature/Server/TunnelTest.php
index 73f543c..3474501 100644
--- a/tests/Feature/Server/TunnelTest.php
+++ b/tests/Feature/Server/TunnelTest.php
@@ -235,8 +235,6 @@ class TunnelTest extends TestCase
             'can_specify_subdomains' => 0,
         ])));
 
-        $this->expectException(\UnexpectedValueException::class);
-
         $user = json_decode($response->getBody()->getContents())->user;
 
         $this->createTestHttpServer();
@@ -248,7 +246,92 @@ class TunnelTest extends TestCase
         $client = $this->createClient();
         $response = $this->await($client->connectToServer('127.0.0.1:8085', 'tunnel', $user->auth_token));
 
-        $this->assertSame('tunnel', $response->subdomain);
+        $this->assertNotSame('tunnel', $response->subdomain);
+    }
+
+    /** @test */
+    public function it_rejects_users_that_want_to_use_a_reserved_subdomain()
+    {
+        $this->app['config']['expose.admin.validate_auth_tokens'] = true;
+
+        $response = $this->await($this->browser->post('http://127.0.0.1:8080/api/users', [
+            'Host' => 'expose.localhost',
+            'Authorization' => base64_encode('username:secret'),
+            'Content-Type' => 'application/json',
+        ], json_encode([
+            'name' => 'Marcel',
+            'can_specify_subdomains' => 1,
+        ])));
+
+        $user = json_decode($response->getBody()->getContents())->user;
+
+        $response = $this->await($this->browser->post('http://127.0.0.1:8080/api/subdomains', [
+            'Host' => 'expose.localhost',
+            'Authorization' => base64_encode('username:secret'),
+            'Content-Type' => 'application/json',
+        ], json_encode([
+            'subdomain' => 'reserved',
+            'auth_token' => $user->auth_token,
+        ])));
+
+        $response = $this->await($this->browser->post('http://127.0.0.1:8080/api/users', [
+            'Host' => 'expose.localhost',
+            'Authorization' => base64_encode('username:secret'),
+            'Content-Type' => 'application/json',
+        ], json_encode([
+            'name' => 'Test-User',
+            'can_specify_subdomains' => 1,
+        ])));
+
+        $user = json_decode($response->getBody()->getContents())->user;
+
+        $this->createTestHttpServer();
+
+        $this->expectException(\UnexpectedValueException::class);
+        /**
+         * We create an expose client that connects to our server and shares
+         * the created test HTTP server.
+         */
+        $client = $this->createClient();
+        $response = $this->await($client->connectToServer('127.0.0.1:8085', 'reserved', $user->auth_token));
+
+        $this->assertSame('reserved', $response->subdomain);
+    }
+
+    /** @test */
+    public function it_allows_users_to_use_their_own_reserved_subdomains()
+    {
+        $this->app['config']['expose.admin.validate_auth_tokens'] = true;
+
+        $response = $this->await($this->browser->post('http://127.0.0.1:8080/api/users', [
+            'Host' => 'expose.localhost',
+            'Authorization' => base64_encode('username:secret'),
+            'Content-Type' => 'application/json',
+        ], json_encode([
+            'name' => 'Marcel',
+            'can_specify_subdomains' => 1,
+        ])));
+
+        $user = json_decode($response->getBody()->getContents())->user;
+
+        $response = $this->await($this->browser->post('http://127.0.0.1:8080/api/subdomains', [
+            'Host' => 'expose.localhost',
+            'Authorization' => base64_encode('username:secret'),
+            'Content-Type' => 'application/json',
+        ], json_encode([
+            'subdomain' => 'reserved',
+            'auth_token' => $user->auth_token,
+        ])));
+
+        $this->createTestHttpServer();
+        /**
+         * We create an expose client that connects to our server and shares
+         * the created test HTTP server.
+         */
+        $client = $this->createClient();
+        $response = $this->await($client->connectToServer('127.0.0.1:8085', 'reserved', $user->auth_token));
+
+        $this->assertSame('reserved', $response->subdomain);
     }
 
     /** @test */