diff --git a/src/ApiResource/ZimbraSettings.php b/src/ApiResource/ZimbraSettings.php
new file mode 100644
index 0000000..5790a06
--- /dev/null
+++ b/src/ApiResource/ZimbraSettings.php
@@ -0,0 +1,51 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\ApiResource;
+
+use ApiPlatform\Metadata\ApiResource;
+use ApiPlatform\Metadata\Get;
+use ApiPlatform\Metadata\Put;
+use App\State\ZimbraSettingsProcessor;
+use App\State\ZimbraSettingsProvider;
+use Symfony\Component\Serializer\Attribute\Groups;
+
+#[ApiResource(
+    operations: [
+        new Get(
+            uriTemplate: '/settings/zimbra',
+            normalizationContext: ['groups' => ['zimbra_settings:read']],
+            provider: ZimbraSettingsProvider::class,
+            security: "is_granted('ROLE_ADMIN')",
+        ),
+        new Put(
+            uriTemplate: '/settings/zimbra',
+            denormalizationContext: ['groups' => ['zimbra_settings:write']],
+            normalizationContext: ['groups' => ['zimbra_settings:read']],
+            provider: ZimbraSettingsProvider::class,
+            processor: ZimbraSettingsProcessor::class,
+            security: "is_granted('ROLE_ADMIN')",
+        ),
+    ],
+)]
+final class ZimbraSettings
+{
+    #[Groups(['zimbra_settings:read', 'zimbra_settings:write'])]
+    public ?string $serverUrl = null;
+
+    #[Groups(['zimbra_settings:read', 'zimbra_settings:write'])]
+    public ?string $username = null;
+
+    #[Groups(['zimbra_settings:read', 'zimbra_settings:write'])]
+    public ?string $calendarPath = null;
+
+    #[Groups(['zimbra_settings:write'])]
+    public ?string $password = null;
+
+    #[Groups(['zimbra_settings:read', 'zimbra_settings:write'])]
+    public bool $enabled = false;
+
+    #[Groups(['zimbra_settings:read'])]
+    public bool $hasPassword = false;
+}
diff --git a/src/ApiResource/ZimbraTestConnection.php b/src/ApiResource/ZimbraTestConnection.php
new file mode 100644
index 0000000..42e9012
--- /dev/null
+++ b/src/ApiResource/ZimbraTestConnection.php
@@ -0,0 +1,28 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\ApiResource;
+
+use ApiPlatform\Metadata\ApiResource;
+use ApiPlatform\Metadata\Post;
+use App\State\ZimbraTestConnectionProvider;
+use Symfony\Component\Serializer\Attribute\Groups;
+
+#[ApiResource(
+    operations: [
+        new Post(
+            uriTemplate: '/settings/zimbra/test',
+            input: false,
+            normalizationContext: ['groups' => ['zimbra_test:read']],
+            provider: ZimbraTestConnectionProvider::class,
+            processor: ZimbraTestConnectionProvider::class,
+            security: "is_granted('ROLE_ADMIN')",
+        ),
+    ],
+)]
+final class ZimbraTestConnection
+{
+    #[Groups(['zimbra_test:read'])]
+    public bool $success = false;
+}
diff --git a/src/State/ZimbraSettingsProcessor.php b/src/State/ZimbraSettingsProcessor.php
new file mode 100644
index 0000000..7825a6b
--- /dev/null
+++ b/src/State/ZimbraSettingsProcessor.php
@@ -0,0 +1,53 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\State;
+
+use ApiPlatform\Metadata\Operation;
+use ApiPlatform\State\ProcessorInterface;
+use App\ApiResource\ZimbraSettings;
+use App\Entity\ZimbraConfiguration;
+use App\Repository\ZimbraConfigurationRepository;
+use App\Service\TokenEncryptor;
+use Doctrine\ORM\EntityManagerInterface;
+
+final readonly class ZimbraSettingsProcessor implements ProcessorInterface
+{
+    public function __construct(
+        private EntityManagerInterface $em,
+        private ZimbraConfigurationRepository $configRepository,
+        private TokenEncryptor $tokenEncryptor,
+    ) {}
+
+    public function process(mixed $data, Operation $operation, array $uriVariables = [], array $context = []): ZimbraSettings
+    {
+        assert($data instanceof ZimbraSettings);
+
+        $config = $this->configRepository->findSingleton();
+        if (null === $config) {
+            $config = new ZimbraConfiguration();
+        }
+
+        $config->setServerUrl($data->serverUrl);
+        $config->setUsername($data->username);
+        $config->setCalendarPath($data->calendarPath);
+        $config->setEnabled($data->enabled);
+
+        if (null !== $data->password && '' !== $data->password) {
+            $config->setEncryptedPassword($this->tokenEncryptor->encrypt($data->password));
+        }
+
+        $this->em->persist($config);
+        $this->em->flush();
+
+        $result               = new ZimbraSettings();
+        $result->serverUrl    = $config->getServerUrl();
+        $result->username     = $config->getUsername();
+        $result->calendarPath = $config->getCalendarPath();
+        $result->enabled      = $config->isEnabled();
+        $result->hasPassword  = $config->hasPassword();
+
+        return $result;
+    }
+}
diff --git a/src/State/ZimbraSettingsProvider.php b/src/State/ZimbraSettingsProvider.php
new file mode 100644
index 0000000..fe95719
--- /dev/null
+++ b/src/State/ZimbraSettingsProvider.php
@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\State;
+
+use ApiPlatform\Metadata\Operation;
+use ApiPlatform\State\ProviderInterface;
+use App\ApiResource\ZimbraSettings;
+use App\Repository\ZimbraConfigurationRepository;
+
+final readonly class ZimbraSettingsProvider implements ProviderInterface
+{
+    public function __construct(
+        private ZimbraConfigurationRepository $configRepository,
+    ) {}
+
+    public function provide(Operation $operation, array $uriVariables = [], array $context = []): ZimbraSettings
+    {
+        $config = $this->configRepository->findSingleton();
+        $dto    = new ZimbraSettings();
+
+        if (null !== $config) {
+            $dto->serverUrl    = $config->getServerUrl();
+            $dto->username     = $config->getUsername();
+            $dto->calendarPath = $config->getCalendarPath();
+            $dto->enabled      = $config->isEnabled();
+            $dto->hasPassword  = $config->hasPassword();
+        }
+
+        return $dto;
+    }
+}
diff --git a/src/State/ZimbraTestConnectionProvider.php b/src/State/ZimbraTestConnectionProvider.php
new file mode 100644
index 0000000..828c64f
--- /dev/null
+++ b/src/State/ZimbraTestConnectionProvider.php
@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\State;
+
+use ApiPlatform\Metadata\Operation;
+use ApiPlatform\State\ProcessorInterface;
+use ApiPlatform\State\ProviderInterface;
+use App\ApiResource\ZimbraTestConnection;
+use App\Service\CalDavService;
+use Throwable;
+
+final readonly class ZimbraTestConnectionProvider implements ProviderInterface, ProcessorInterface
+{
+    public function __construct(
+        private CalDavService $calDavService,
+    ) {}
+
+    public function provide(Operation $operation, array $uriVariables = [], array $context = []): ZimbraTestConnection
+    {
+        return new ZimbraTestConnection();
+    }
+
+    public function process(mixed $data, Operation $operation, array $uriVariables = [], array $context = []): ZimbraTestConnection
+    {
+        $result = new ZimbraTestConnection();
+
+        try {
+            $result->success = $this->calDavService->testConnection();
+        } catch (Throwable) {
+            $result->success = false;
+        }
+
+        return $result;
+    }
+}