diff --git a/application/controllers/ApiV1ChannelsController.php b/application/controllers/ApiV1ChannelsController.php
new file mode 100644
index 00000000..ef3ee417
--- /dev/null
+++ b/application/controllers/ApiV1ChannelsController.php
@@ -0,0 +1,141 @@
+<?php
+
+/* Icinga Notifications Web | (c) 2024 Icinga GmbH | GPLv2 */
+
+namespace Icinga\Module\Notifications\Controllers;
+
+use Exception;
+use Icinga\Module\Notifications\Common\Database;
+use Icinga\Util\Environment;
+use Icinga\Util\Json;
+use ipl\Sql\Compat\FilterProcessor;
+use ipl\Sql\Select;
+use ipl\Stdlib\Filter;
+use ipl\Web\Compat\CompatController;
+use ipl\Web\Filter\QueryString;
+use ipl\Web\Url;
+use Ramsey\Uuid\Uuid;
+use stdClass;
+
+class ApiV1ChannelsController extends CompatController
+{
+    public function indexAction(): void
+    {
+        $this->assertPermission('notifications/api/v1');
+
+        $request = $this->getRequest();
+        if (! $request->isApiRequest()) {
+            $this->httpBadRequest('No API request');
+        }
+
+        $method = $request->getMethod();
+        if ($method !== 'GET') {
+            $this->httpBadRequest('Only GET method supported');
+        }
+
+        $db = Database::get();
+
+        /** @var ?string $identifier */
+        $identifier = $request->getParam('identifier');
+
+        if ($identifier && ! Uuid::isValid($identifier)) {
+            $this->httpBadRequest('The given identifier is not a valid UUID');
+        }
+
+        try {
+            $filterRule = QueryString::fromString(Url::fromRequest()->getQueryString())
+                ->on(
+                    QueryString::ON_CONDITION,
+                    function (Filter\Condition $condition) {
+                        $column = $condition->getColumn();
+                        if (! in_array($column, ['id', 'name', 'type'])) {
+                            $this->httpBadRequest(sprintf(
+                                'Invalid filter column %s given, only id, name and type are allowed',
+                                $column
+                            ));
+                        }
+
+                        if ($column === 'id') {
+                            if (! Uuid::isValid($condition->getValue())) {
+                                $this->httpBadRequest('The given filter id is not a valid UUID');
+                            }
+
+                            $condition->setColumn('external_uuid');
+                        }
+                    }
+                )->parse();
+
+            $filter = FilterProcessor::assembleFilter($filterRule);
+        } catch (Exception $e) {
+            $this->httpBadRequest($e->getMessage());
+        }
+
+        $stmt = (new Select())
+            ->distinct()
+            ->from('channel ch')
+            ->columns([
+                'channel_id'    => 'ch.id',
+                'id'            => 'ch.external_uuid',
+                'name',
+                'type',
+                'config'
+            ]);
+
+        if ($identifier !== null) {
+            $stmt->where(['external_uuid = ?' => $identifier]);
+
+            /** @var stdClass|false $result */
+            $result = $db->fetchOne($stmt);
+
+            if ($result === false) {
+                $this->httpNotFound('Channel not found');
+            }
+
+            unset($result->channel_id);
+
+            $this->getResponse()
+                ->setHttpResponseCode(200)
+                ->json()
+                ->setSuccessData((array) $result)
+                ->sendResponse();
+        } else {
+            if ($filter !== null) {
+                $stmt->where($filter);
+            }
+
+            $stmt->limit(500);
+            $offset = 0;
+
+            ob_end_clean();
+            Environment::raiseExecutionTime();
+
+            $this->getResponse()
+                ->setHeader('Content-Type', 'application/json')
+                ->setHeader('Cache-Control', 'no-store')
+                ->sendResponse();
+
+            echo '[';
+
+            $res = $db->select($stmt->offset($offset));
+            do {
+                /** @var stdClass $row */
+                foreach ($res as $i => $row) {
+                    if ($i > 0 || $offset !== 0) {
+                        echo ",\n";
+                    }
+
+                    unset($row->channel_id);
+
+                    echo Json::sanitize($row);
+                }
+
+                $offset += 500;
+                $res = $db->select($stmt->offset($offset));
+            } while ($res->rowCount());
+
+            echo ']';
+        }
+
+        exit;
+    }
+}
diff --git a/application/controllers/ApiV1ContactgroupsController.php b/application/controllers/ApiV1ContactgroupsController.php
new file mode 100644
index 00000000..6492be3c
--- /dev/null
+++ b/application/controllers/ApiV1ContactgroupsController.php
@@ -0,0 +1,445 @@
+<?php
+
+/* Icinga Notifications Web | (c) 2024 Icinga GmbH | GPLv2 */
+
+namespace Icinga\Module\Notifications\Controllers;
+
+use Exception;
+use Icinga\Exception\Http\HttpBadRequestException;
+use Icinga\Exception\Http\HttpException;
+use Icinga\Exception\Http\HttpNotFoundException;
+use Icinga\Module\Notifications\Common\Database;
+use Icinga\Util\Environment;
+use Icinga\Util\Json;
+use ipl\Sql\Compat\FilterProcessor;
+use ipl\Sql\Select;
+use ipl\Stdlib\Filter;
+use ipl\Web\Compat\CompatController;
+use ipl\Web\Filter\QueryString;
+use ipl\Web\Url;
+use Ramsey\Uuid\Uuid;
+use stdClass;
+
+/** @phpstan-type requestBody array{
+ *  id: string,
+ *  name: string,
+ *  users?: string[],
+ *  }
+ */
+class ApiV1ContactgroupsController extends CompatController
+{
+    private const ENDPOINT = 'notifications/api/v1/contactgroups';
+
+    public function indexAction(): void
+    {
+        $this->assertPermission('notifications/api/v1');
+
+        $request = $this->getRequest();
+        if (! $request->isApiRequest()) {
+            $this->httpBadRequest('No API request');
+        }
+
+        $method = $request->getMethod();
+        if (
+            in_array($method, ['POST', 'PUT'])
+            && (
+                ! preg_match('/([^;]*);?/', $request->getHeader('Content-Type'), $matches)
+                || $matches[1] !== 'application/json'
+            )
+        ) {
+            $this->httpBadRequest('No JSON content');
+        }
+
+        $results = [];
+        $responseCode = 200;
+        $db = Database::get();
+
+        /** @var ?string $identifier */
+        $identifier = $request->getParam('identifier');
+
+        if ($identifier && ! Uuid::isValid($identifier)) {
+            $this->httpBadRequest('The given identifier is not a valid UUID');
+        }
+
+        $filterStr = Url::fromRequest()->getQueryString();
+        if ($method !== 'GET' && $filterStr) {
+            $this->httpBadRequest('Filter is only allowed for GET requests');
+        }
+
+        try {
+            $filterRule = QueryString::fromString($filterStr)
+                ->on(
+                    QueryString::ON_CONDITION,
+                    function (Filter\Condition $condition) {
+                        $column = $condition->getColumn();
+                        if (! in_array($column, ['id', 'name'])) {
+                            $this->httpBadRequest(sprintf(
+                                'Invalid filter column %s given, only id and name are allowed',
+                                $column
+                            ));
+                        }
+
+                        if ($column === 'id') {
+                            if (! Uuid::isValid($condition->getValue())) {
+                                $this->httpBadRequest('The given filter id is not a valid UUID');
+                            }
+
+                            $condition->setColumn('external_uuid');
+                        }
+                    }
+                )->parse();
+
+            $filter = FilterProcessor::assembleFilter($filterRule);
+        } catch (Exception $e) {
+            $this->httpBadRequest($e->getMessage());
+        }
+
+        switch ($method) {
+            case 'GET':
+                $stmt = (new Select())
+                    ->distinct()
+                    ->from('contactgroup cg')
+                    ->columns([
+                        'contactgroup_id'   => 'cg.id',
+                        'id'                => 'cg.external_uuid',
+                        'name'
+                    ]);
+
+                if ($identifier !== null) {
+                    $stmt->where(['external_uuid = ?' => $identifier]);
+
+                    /** @var stdClass|false $result */
+                    $result = $db->fetchOne($stmt);
+
+                    if ($result === false) {
+                        $this->httpNotFound('Contactgroup not found');
+                    }
+
+                    $result->users = $this->fetchUserIdentifiers($result->contactgroup_id);
+
+                    unset($result->contactgroup_id);
+                    $results[] = $result;
+
+                    break;
+                }
+
+                if ($filter !== null) {
+                    $stmt->where($filter);
+                }
+
+                $stmt->limit(500);
+                $offset = 0;
+
+                ob_end_clean();
+                Environment::raiseExecutionTime();
+
+                $this->getResponse()
+                    ->setHeader('Content-Type', 'application/json')
+                    ->setHeader('Cache-Control', 'no-store')
+                    ->sendResponse();
+
+                echo '[';
+
+                $res = $db->select($stmt->offset($offset));
+                do {
+                    /** @var stdClass $row */
+                    foreach ($res as $i => $row) {
+                        $row->users = $this->fetchUserIdentifiers($row->contactgroup_id);
+
+                        if ($i > 0 || $offset !== 0) {
+                            echo ",\n";
+                        }
+
+                        unset($row->contactgroup_id);
+
+                        echo Json::sanitize($row);
+                    }
+
+                    $offset += 500;
+                    $res = $db->select($stmt->offset($offset));
+                } while ($res->rowCount());
+
+                echo ']';
+
+                exit;
+            case 'POST':
+                if ($filter !== null) {
+                    $this->httpBadRequest('Cannot filter on POST');
+                }
+
+                $data = $this->getValidatedData();
+
+                $db->beginTransaction();
+
+                if ($identifier === null) {
+                    if ($this->getContactgroupId($data['id']) !== null) {
+                        throw new HttpException(422, 'Contactgroup already exists');
+                    }
+
+                    $this->addContactgroup($data);
+                } else {
+                    $contactgroupId = $this->getContactgroupId($identifier);
+                    if ($contactgroupId === null) {
+                        $this->httpNotFound('Contactgroup not found');
+                    }
+
+                    if ($identifier === $data['id'] || $this->getContactgroupId($data['id']) !== null) {
+                        throw new HttpException(422, 'Contactgroup already exists');
+                    }
+
+                    $this->removeContactgroup($contactgroupId);
+                    $this->addContactgroup($data);
+                }
+
+                $db->commitTransaction();
+
+                $this->getResponse()->setHeader('Location', self::ENDPOINT . '/' . $data['id']);
+                $responseCode = 201;
+
+                break;
+            case 'PUT':
+                if ($identifier === null) {
+                    $this->httpBadRequest('Identifier is required');
+                }
+
+                $data = $this->getValidatedData();
+
+                if ($identifier !== $data['id']) {
+                    $this->httpBadRequest('Identifier mismatch');
+                }
+
+                $db->beginTransaction();
+
+                $contactgroupId = $this->getContactgroupId($identifier);
+                if ($contactgroupId !== null) {
+                    $db->update('contactgroup', ['name' => $data['name']], ['id = ?' => $contactgroupId]);
+                    $db->update('contactgroup_member', ['deleted' => 'y'], ['contactgroup_id = ?' => $contactgroupId, 'deleted = ?' => 'n']);
+
+                    if (! empty($data['users'])) {
+                        $this->addUsers($contactgroupId, $data['users']);
+                    }
+
+                    $responseCode = 204;
+                } else {
+                    $this->addContactgroup($data);
+                    $responseCode = 201;
+                }
+
+                $db->commitTransaction();
+
+                break;
+            case 'DELETE':
+                if ($identifier === null) {
+                    $this->httpBadRequest('Identifier is required');
+                }
+
+                $db->beginTransaction();
+
+                $contactgroupId = $this->getContactgroupId($identifier);
+                if ($contactgroupId === null) {
+                    $this->httpNotFound('Contactgroup not found');
+                }
+
+                $this->removeContactgroup($contactgroupId);
+
+                $db->commitTransaction();
+
+                $responseCode = 204;
+
+                break;
+            default:
+                $this->httpBadRequest('Invalid method');
+        }
+
+        $this->getResponse()
+            ->setHttpResponseCode($responseCode)
+            ->json()
+            ->setSuccessData($results)
+            ->sendResponse();
+    }
+
+    /**
+     * Fetch the user(contact) identifiers of the contactgroup with the given id
+     *
+     * @param int $contactgroupId
+     *
+     * @return string[]
+     */
+    private function fetchUserIdentifiers(int $contactgroupId): array
+    {
+        return Database::get()->fetchCol(
+            (new Select())
+                ->from('contactgroup_member cgm')
+                ->columns('co.external_uuid')
+                ->joinLeft('contact co', 'co.id = cgm.contact_id')
+                ->where(['cgm.contactgroup_id = ?' => $contactgroupId])
+                ->groupBy('co.external_uuid')
+        );
+    }
+
+    /**
+     * Assert that the given user IDs exist
+     *
+     * @param string $identifier
+     *
+     * @return int
+     *
+     * @throws HttpNotFoundException if the user with the given identifier does not exist
+     */
+    private function getUserId(string $identifier): int
+    {
+        /** @var stdClass|false $user */
+        $user = Database::get()->fetchOne(
+            (new Select())
+                ->from('contact')
+                ->columns('id')
+                ->where(['external_uuid = ?' => $identifier])
+        );
+
+        if ($user === false) {
+            $this->httpNotFound(sprintf('User with identifier %s not found', $identifier));
+        }
+
+        return $user->id;
+    }
+
+    /**
+     * Get the contactgroup id with the given identifier
+     *
+     * @param string $identifier
+     *
+     * @return ?int Returns null, if contact does not exist
+     */
+    private function getContactgroupId(string $identifier): ?int
+    {
+        /** @var stdClass|false $contactgroup */
+        $contactgroup =  Database::get()->fetchOne(
+            (new Select())
+                ->from('contactgroup')
+                ->columns('id')
+                ->where(['external_uuid = ?' => $identifier])
+        );
+
+        return $contactgroup->id ?? null;
+    }
+
+    /**
+     * Add a new contactgroup with the given data
+     *
+     * @param requestBody $data
+     *
+     * @return void
+     */
+    private function addContactgroup(array $data): void
+    {
+        Database::get()->insert('contactgroup', [
+            'name'              => $data['name'],
+            'external_uuid'     => $data['id']
+        ]);
+
+        $id = Database::get()->lastInsertId();
+
+        if (! empty($data['users'])) {
+            $this->addUsers($id, $data['users']);
+        }
+    }
+
+    /**
+     * Add the given users as contactgroup_member with the given id
+     *
+     * @param int $contactgroupId
+     * @param string[] $users
+     *
+     * @return void
+     */
+    private function addUsers(int $contactgroupId, array $users): void
+    {
+        foreach ($users as $identifier) {
+            $contactId = $this->getUserId($identifier);
+
+            Database::get()->insert('contactgroup_member', [
+                'contactgroup_id'   => $contactgroupId,
+                'contact_id'        => $contactId
+            ]);
+        }
+    }
+
+    /**
+     * Remove the contactgroup with the given id
+     *
+     * @param int $id
+     *
+     * @return void
+     */
+    private function removeContactgroup(int $id): void
+    {
+        $db = Database::get();
+        $markAsDeleted = ['deleted' => 'y'];
+
+        $db->update(
+            'rotation_member',
+            $markAsDeleted + ['position' => null],
+            ['contactgroup_id = ?' => $id, 'deleted = ?' => 'n']
+        );
+
+        $db->update(
+            'rule_escalation_recipient',
+            $markAsDeleted,
+            ['contactgroup_id = ?' => $id, 'deleted = ?' => 'n']
+        );
+
+        $db->update('contactgroup_member', $markAsDeleted, ['contactgroup_id = ?' => $id, 'deleted = ?' => 'n']);
+        $db->update('contactgroup', $markAsDeleted, ['id = ?' => $id]);
+
+        //TODO: properly remove rotations|escalations with no members as in form
+    }
+
+    /**
+     * Get the validated POST|PUT request data
+     *
+     * @return requestBody
+     *
+     * @throws HttpBadRequestException if the request body is invalid
+     */
+    private function getValidatedData(): array
+    {
+        $msgPrefix = 'Invalid request body: ';
+
+        try {
+            $data = $this->getRequest()->getPost();
+        } catch (Exception $e) {
+            $this->httpBadRequest($msgPrefix . 'given content is not a valid JSON');
+        }
+
+        if (
+            ! isset($data['id'], $data['name'])
+            || ! is_string($data['id'])
+            || ! is_string($data['name'])
+        ) {
+            $this->httpBadRequest(
+                $msgPrefix . 'the fields id and name must be present and of type string'
+            );
+        }
+
+        if (! Uuid::isValid($data['id'])) {
+            $this->httpBadRequest($msgPrefix . 'given id is not a valid UUID');
+        }
+
+        if (! empty($data['users'])) {
+            if (! is_array($data['users'])) {
+                $this->httpBadRequest($msgPrefix .  'expects users to be an array');
+            }
+
+            foreach ($data['users'] as $user) {
+                if (! is_string($user) || ! Uuid::isValid($user)) {
+                    $this->httpBadRequest($msgPrefix . 'user identifiers must be valid UUIDs');
+                }
+
+                //TODO: check if users exist, here?
+            }
+        }
+
+        /** @var requestBody $data */
+        return $data;
+    }
+}
diff --git a/application/controllers/ApiV1ContactsController.php b/application/controllers/ApiV1ContactsController.php
new file mode 100644
index 00000000..44a82eb7
--- /dev/null
+++ b/application/controllers/ApiV1ContactsController.php
@@ -0,0 +1,609 @@
+<?php
+
+/* Icinga Notifications Web | (c) 2024 Icinga GmbH | GPLv2 */
+
+namespace Icinga\Module\Notifications\Controllers;
+
+use Exception;
+use Icinga\Exception\Http\HttpBadRequestException;
+use Icinga\Exception\Http\HttpException;
+use Icinga\Exception\Http\HttpNotFoundException;
+use Icinga\Module\Notifications\Common\Database;
+use Icinga\Util\Environment;
+use Icinga\Util\Json;
+use ipl\Sql\Compat\FilterProcessor;
+use ipl\Sql\Select;
+use ipl\Stdlib\Filter;
+use ipl\Validator\EmailAddressValidator;
+use ipl\Web\Compat\CompatController;
+use ipl\Web\Filter\QueryString;
+use ipl\Web\Url;
+use Ramsey\Uuid\Uuid;
+use stdClass;
+
+/**
+ * @phpstan-type requestBody array{
+ *       id: string,
+ *       full_name: string,
+ *       default_channel: string,
+ *       username?: string,
+ *       groups?: string[],
+ *       addresses?: array<string,string>
+ *   }
+ */
+class ApiV1ContactsController extends CompatController
+{
+    private const ENDPOINT = 'notifications/api/v1/contacts';
+
+    public function indexAction(): void
+    {
+        $this->assertPermission('notifications/api/v1');
+
+        $request = $this->getRequest();
+        if (! $request->isApiRequest()) {
+            $this->httpBadRequest('No API request');
+        }
+
+        $method = $request->getMethod();
+        if (
+            in_array($method, ['POST', 'PUT'])
+            && (
+                ! preg_match('/([^;]*);?/', $request->getHeader('Content-Type'), $matches)
+                || $matches[1] !== 'application/json'
+            )
+        ) {
+            $this->httpBadRequest('No JSON content');
+        }
+
+        $results = [];
+        $responseCode = 200;
+        $db = Database::get();
+
+        /** @var ?string $identifier */
+        $identifier = $request->getParam('identifier');
+
+        if ($identifier && ! Uuid::isValid($identifier)) {
+            $this->httpBadRequest('The given identifier is not a valid UUID');
+        }
+
+        $filterStr = Url::fromRequest()->getQueryString();
+        if ($method !== 'GET' && $filterStr) {
+            $this->httpBadRequest('Filter is only allowed for GET requests');
+        }
+
+        try {
+            $filterRule = QueryString::fromString($filterStr)
+                ->on(
+                    QueryString::ON_CONDITION,
+                    function (Filter\Condition $condition) {
+                        $column = $condition->getColumn();
+                        if (! in_array($column, ['id', 'full_name', 'username'])) {
+                            $this->httpBadRequest(sprintf(
+                                'Invalid filter column %s given, only id, full_name and username are allowed',
+                                $column
+                            ));
+                        }
+
+                        if ($column === 'id') {
+                            if (! Uuid::isValid($condition->getValue())) {
+                                $this->httpBadRequest('The given filter id is not a valid UUID');
+                            }
+
+                            $condition->setColumn('external_uuid');
+                        }
+                    }
+                )->parse();
+
+            $filter = FilterProcessor::assembleFilter($filterRule);
+        } catch (Exception $e) {
+            $this->httpBadRequest($e->getMessage());
+        }
+
+        switch ($method) {
+            case 'GET':
+                $stmt = (new Select())
+                    ->distinct()
+                    ->from('contact co')
+                    ->columns([
+                        'contact_id'        => 'co.id',
+                        'id'                => 'co.external_uuid',
+                        'full_name',
+                        'username',
+                        'default_channel'   => 'ch.external_uuid',
+                    ])
+                    ->joinLeft('contact_address ca', 'ca.contact_id = co.id')
+                    ->joinLeft('channel ch', 'ch.id = co.default_channel_id');
+
+                if ($identifier !== null) {
+                    $stmt->where(['external_uuid = ?' => $identifier]);
+
+                    /** @var stdClass|false $result */
+                    $result = $db->fetchOne($stmt);
+
+                    if ($result === false) {
+                        $this->httpNotFound('Contact not found');
+                    }
+
+                    $result->groups = $this->fetchGroupIdentifiers($result->contact_id);
+                    $result->addresses = $this->fetchContactAddresses($result->contact_id);
+
+                    unset($result->contact_id);
+                    $results[] = $result;
+
+                    break;
+                }
+
+                if ($filter !== null) {
+                    $stmt->where($filter);
+                }
+
+                $stmt->limit(500);
+                $offset = 0;
+
+                ob_end_clean();
+                Environment::raiseExecutionTime();
+
+                $this->getResponse()
+                    ->setHeader('Content-Type', 'application/json')
+                    ->setHeader('Cache-Control', 'no-store')
+                    ->sendResponse();
+
+                echo '[';
+
+                $res = $db->select($stmt->offset($offset));
+                do {
+                    /** @var stdClass $row */
+                    foreach ($res as $i => $row) {
+                        $row->groups = $this->fetchGroupIdentifiers($row->contact_id);
+                        $row->addresses = $this->fetchContactAddresses($row->contact_id);
+
+                        if ($i > 0 || $offset !== 0) {
+                            echo ",\n";
+                        }
+
+                        unset($row->contact_id);
+
+                        echo Json::sanitize($row);
+                    }
+
+                    $offset += 500;
+                    $res = $db->select($stmt->offset($offset));
+                } while ($res->rowCount());
+
+                echo ']';
+
+                exit;
+            case 'POST':
+                $data = $this->getValidatedData();
+
+                $db->beginTransaction();
+
+                if ($identifier === null) {
+                    if ($this->getContactId($data['id']) !== null) {
+                        throw new HttpException(422, 'Contact already exists');
+                    }
+
+                    $this->addContact($data);
+                } else {
+                    $contactId = $this->getContactId($identifier);
+                    if ($contactId === null) {
+                        $this->httpNotFound('Contact not found');
+                    }
+
+                    if ($identifier === $data['id'] || $this->getContactId($data['id']) !== null) {
+                        throw new HttpException(422, 'Contact already exists');
+                    }
+
+                    $this->removeContact($contactId);
+                    $this->addContact($data);
+                }
+
+                $db->commitTransaction();
+
+                $this->getResponse()->setHeader('Location', self::ENDPOINT . '/' . $data['id']);
+                $responseCode = 201;
+
+                break;
+            case 'PUT':
+                if ($identifier === null) {
+                    $this->httpBadRequest('Identifier is required');
+                }
+
+                $data = $this->getValidatedData();
+
+                if ($identifier !== $data['id']) {
+                    $this->httpBadRequest('Identifier mismatch');
+                }
+
+                $db->beginTransaction();
+
+                $contactId = $this->getContactId($identifier);
+                if ($contactId !== null) {
+                    if (! empty($data['username'])) {
+                        $this->assertUniqueUsername($data['username'], $contactId);
+                    }
+
+                    $db->update('contact', [
+                        'full_name'             => $data['full_name'],
+                        'username'              => $data['username'] ?? null,
+                        'default_channel_id'    => $this->getChannelId($data['default_channel']),
+                    ], ['id = ?' => $contactId]);
+
+                    $markAsDeleted = ['deleted' => 'y'];
+                    $db->update('contact_address', $markAsDeleted, ['contact_id = ?' => $contactId, 'deleted = ?' => 'n']);
+                    $db->update('contactgroup_member', $markAsDeleted, ['contact_id = ?' => $contactId, 'deleted = ?' => 'n']);
+
+                    if (! empty($data['addresses'])) {
+                        $this->addAddresses($contactId, $data['addresses']);
+                    }
+
+                    if (! empty($data['groups'])) {
+                        $this->addGroups($contactId, $data['groups']);
+                    }
+
+                    $responseCode = 204;
+                } else {
+                    $this->addContact($data);
+                    $responseCode = 201;
+                }
+
+                $db->commitTransaction();
+
+                break;
+            case 'DELETE':
+                if ($identifier === null) {
+                    $this->httpBadRequest('Identifier is required');
+                }
+
+                $db->beginTransaction();
+
+                $contactId = $this->getContactId($identifier);
+                if ($contactId === null) {
+                    $this->httpNotFound('Contact not found');
+                }
+
+                $this->removeContact($contactId);
+
+                $db->commitTransaction();
+
+                $responseCode = 204;
+
+                break;
+            default:
+                $this->httpBadRequest('Invalid method');
+        }
+
+        $this->getResponse()
+            ->setHttpResponseCode($responseCode)
+            ->json()
+            ->setSuccessData($results)
+            ->sendResponse();
+    }
+
+    /**
+     * Get the channel id with the given identifier
+     *
+     * @param string $channelIdentifier
+     *
+     * @return int
+     *
+     * @throws HttpNotFoundException if the channel does not exist
+     */
+    private function getChannelId(string $channelIdentifier): int
+    {
+        /** @var stdClass|false $channel */
+        $channel = Database::get()->fetchOne(
+            (new Select())
+                ->from('channel')
+                ->columns('id')
+                ->where(['external_uuid = ?' => $channelIdentifier])
+        );
+
+        if ($channel === false) {
+            $this->httpNotFound('Channel not found');
+        }
+
+        return $channel->id;
+    }
+
+    /**
+     * Fetch the addresses of the contact with the given id
+     *
+     * @param int $contactId
+     *
+     * @return string
+     */
+    private function fetchContactAddresses(int $contactId): string
+    {
+        /** @var array<string, string> $addresses */
+        $addresses = Database::get()->fetchPairs(
+            (new Select())
+                ->from('contact_address')
+                ->columns(['type', 'address'])
+                ->where(['contact_id = ?' => $contactId])
+        );
+
+        return Json::sanitize($addresses, JSON_FORCE_OBJECT);
+    }
+
+    /**
+     * Fetch the group identifiers of the contact with the given id
+     *
+     * @param int $contactId
+     *
+     * @return string[]
+     */
+    private function fetchGroupIdentifiers(int $contactId): array
+    {
+        return Database::get()->fetchCol(
+            (new Select())
+                ->from('contactgroup_member cgm')
+                ->columns('cg.external_uuid')
+                ->joinLeft('contactgroup cg', 'cg.id = cgm.contactgroup_id')
+                ->where(['cgm.contact_id = ?' => $contactId])
+                ->groupBy('cg.external_uuid')
+        );
+    }
+
+    /**
+     * Get the group id with the given identifier
+     *
+     * @param string $identifier
+     *
+     * @return int
+     *
+     * @throws HttpNotFoundException if the contactgroup with the given identifier does not exist
+     */
+    private function getGroupId(string $identifier): int
+    {
+        /** @var stdClass|false $group */
+        $group = Database::get()->fetchOne(
+            (new Select())
+                ->from('contactgroup')
+                ->columns('id')
+                ->where(['external_uuid = ?' => $identifier])
+        );
+
+        if ($group === false) {
+            $this->httpNotFound(sprintf('Group with identifier %s not found', $identifier));
+        }
+
+        return $group->id;
+    }
+
+    /**
+     * Get the contact id with the given identifier
+     *
+     * @param string $identifier
+     *
+     * @return ?int Returns null, if contact does not exist
+     */
+    protected function getContactId(string $identifier): ?int
+    {
+        /** @var stdClass|false $contact */
+        $contact =  Database::get()->fetchOne(
+            (new Select())
+                ->from('contact')
+                ->columns('id')
+                ->where(['external_uuid = ?' => $identifier])
+        );
+
+        return $contact->id ?? null;
+    }
+
+    /**
+     * Add a new contact with the given data
+     *
+     * @param requestBody $data
+     *
+     * @return void
+     */
+    private function addContact(array $data): void
+    {
+        if (! empty($data['username'])) {
+            $this->assertUniqueUsername($data['username']);
+        }
+
+        Database::get()->insert('contact', [
+            'full_name'             => $data['full_name'],
+            'username'              => $data['username'] ?? null,
+            'default_channel_id'    => $this->getChannelId($data['default_channel']),
+            'external_uuid'         => $data['id']
+        ]);
+
+        $contactId = Database::get()->lastInsertId();
+
+        if (! empty($data['addresses'])) {
+            $this->addAddresses($contactId, $data['addresses']);
+        }
+
+        if (! empty($data['groups'])) {
+            $this->addGroups($contactId, $data['groups']);
+        }
+    }
+
+    /**
+     * Assert that the username is unique
+     *
+     * @param string $username
+     * @param int $contactId The id of the contact to exclude
+     *
+     * @return void
+     *
+     * @throws HttpException if the username already exists
+     */
+    private function assertUniqueUsername(string $username, int $contactId = null): void
+    {
+        $stmt = (new Select())
+            ->from('contact')
+            ->columns('1')
+            ->where(['username = ?' => $username]);
+
+        if ($contactId) {
+            $stmt->where(['id != ?' => $contactId]);
+        }
+
+        $user = Database::get()->fetchOne($stmt);
+
+        if ($user !== false) {
+            throw new HttpException(422, 'Username already exists');
+        }
+    }
+
+    /**
+     * Add the groups to the given contact
+     *
+     * @param int $contactId
+     * @param string[] $groups
+     *
+     * @return void
+     */
+    private function addGroups(int $contactId, array $groups): void
+    {
+        foreach ($groups as $groupIdentifier) {
+            $groupId = $this->getGroupId($groupIdentifier);
+
+            Database::get()->insert('contactgroup_member', [
+                'contact_id'        => $contactId,
+                'contactgroup_id'   => $groupId
+            ]);
+        }
+    }
+
+    /**
+     * Add the addresses to the given contact
+     *
+     * @param int $contactId
+     * @param array<string, string> $addresses
+     *
+     * @return void
+     */
+    private function addAddresses(int $contactId, array $addresses): void
+    {
+        foreach ($addresses as $type => $address) {
+            Database::get()->insert('contact_address', [
+                'contact_id'    => $contactId,
+                'type'          => $type,
+                'address'       => $address
+            ]);
+        }
+    }
+
+    /**
+     * Remove the contact with the given id
+     *
+     * @param int $id
+     *
+     * @return void
+     */
+    private function removeContact(int $id): void
+    {
+        $db = Database::get();
+        $markAsDeleted = ['deleted' => 'y'];
+
+        $db->update(
+            'rotation_member',
+            $markAsDeleted + ['position' => null],
+            ['contact_id = ?' => $id, 'deleted = ?' => 'n']
+        );
+
+        $db->update(
+            'rule_escalation_recipient',
+            $markAsDeleted,
+            ['contact_id = ?' => $id, 'deleted = ?' => 'n']
+        );
+
+        $db->update('contactgroup_member', $markAsDeleted, ['contact_id = ?' => $id, 'deleted = ?' => 'n']);
+        $db->update('contact_address', $markAsDeleted, ['contact_id = ?' => $id, 'deleted = ?' => 'n']);
+        $db->update('contact', $markAsDeleted, ['id = ?' => $id]);
+
+        //TODO: properly remove rotations|escalations with no members as in form
+    }
+
+    /**
+     * Get the validated POST|PUT request data
+     *
+     * @return requestBody
+     *
+     * @throws HttpBadRequestException if the request body is invalid
+     */
+    private function getValidatedData(): array
+    {
+        $msgPrefix = 'Invalid request body: ';
+
+        try {
+            $data = $this->getRequest()->getPost();
+        } catch (Exception $e) {
+            $this->httpBadRequest($msgPrefix . 'given content is not a valid JSON');
+        }
+
+        if (
+            ! isset($data['id'], $data['full_name'], $data['default_channel'])
+            || ! is_string($data['id'])
+            || ! is_string($data['full_name'])
+            || ! is_string($data['default_channel'])
+        ) {
+            $this->httpBadRequest(
+                $msgPrefix . 'the fields id, full_name and default_channel must be present and of type string'
+            );
+        }
+
+        if (! Uuid::isValid($data['id'])) {
+            $this->httpBadRequest($msgPrefix . 'given id is not a valid UUID');
+        }
+
+        if (! Uuid::isValid($data['default_channel'])) {
+            $this->httpBadRequest($msgPrefix . 'given default_channel is not a valid UUID');
+        }
+
+        if (! empty($data['username']) && ! is_string($data['username'])) {
+            $this->httpBadRequest($msgPrefix . 'expects username to be a string');
+        }
+
+        if (! empty($data['groups'])) {
+            if (! is_array($data['groups'])) {
+                $this->httpBadRequest($msgPrefix . 'expects groups to be an array');
+            }
+
+            foreach ($data['groups'] as $group) {
+                if (! is_string($group) || ! Uuid::isValid($group)) {
+                    $this->httpBadRequest($msgPrefix . 'group identifiers must be valid UUIDs');
+                }
+            }
+        }
+
+        if (! empty($data['addresses'])) {
+            if (! is_array($data['addresses'])) {
+                $this->httpBadRequest($msgPrefix . 'expects addresses to be an array');
+            }
+
+            $addressTypes = array_keys($data['addresses']);
+
+            $types = Database::get()->fetchCol(
+                (new Select())
+                    ->from('available_channel_type')
+                    ->columns('type')
+                    ->where(['type IN (?)' => $addressTypes])
+            );
+
+            if (count($types) !== count($addressTypes)) {
+                $this->httpBadRequest(sprintf(
+                    $msgPrefix . 'undefined address type %s given',
+                    implode(', ', array_diff($addressTypes, $types))
+                ));
+            }
+            //TODO: is it a good idea to check valid channel types here?, if yes,
+            //default_channel and group identifiers must be checked here as well..404 OR 400?
+
+            if (
+                ! empty($data['addresses']['email'])
+                && ! (new EmailAddressValidator())->isValid($data['addresses']['email'])
+            ) {
+                $this->httpBadRequest($msgPrefix . 'an invalid email address given');
+            }
+        }
+
+        /** @var requestBody $data */
+        return $data;
+    }
+}
diff --git a/application/forms/ChannelForm.php b/application/forms/ChannelForm.php
index 7b03b7e1..e413aaec 100644
--- a/application/forms/ChannelForm.php
+++ b/application/forms/ChannelForm.php
@@ -20,6 +20,7 @@
 use ipl\Validator\EmailAddressValidator;
 use ipl\Web\Common\CsrfCounterMeasure;
 use ipl\Web\Compat\CompatForm;
+use Ramsey\Uuid\Uuid;
 
 /**
  * @phpstan-type ChannelOptionConfig array{
@@ -201,6 +202,7 @@ public function addChannel(): void
 
         $channel['config'] = json_encode($this->filterConfig($channel['config']));
         $channel['changed_at'] = time() * 1000;
+        $channel['external_uuid'] = Uuid::uuid4()->toString();
 
         $this->db->insert('channel', $channel);
     }
diff --git a/application/forms/ContactGroupForm.php b/application/forms/ContactGroupForm.php
index d7d63ed8..7a462c2c 100644
--- a/application/forms/ContactGroupForm.php
+++ b/application/forms/ContactGroupForm.php
@@ -22,6 +22,7 @@
 use ipl\Web\Compat\CompatForm;
 use ipl\Web\FormElement\TermInput;
 use ipl\Web\FormElement\TermInput\Term;
+use Ramsey\Uuid\Uuid;
 
 class ContactGroupForm extends CompatForm
 {
@@ -179,7 +180,13 @@ public function addGroup(): int
         $this->db->beginTransaction();
 
         $changedAt = time() * 1000;
-        $this->db->insert('contactgroup', ['name' => trim($data['group_name']), 'changed_at' => $changedAt]);
+        $this->db->insert(
+            'contactgroup',
+            [
+                'name'          => $data['group_name'],
+                'external_uuid' => Uuid::uuid4()->toString()
+            ]
+        );
 
         $groupIdentifier = $this->db->lastInsertId();
 
diff --git a/configuration.php b/configuration.php
index 5d098aeb..c62c8ad9 100644
--- a/configuration.php
+++ b/configuration.php
@@ -42,6 +42,11 @@
     $this->translate('Allow to configure contact groups')
 );
 
+$this->providePermission(
+    'notifications/api/v1',
+    $this->translate('Allow to modify configuration via API')
+);
+
 $this->provideRestriction(
     'notifications/filter/objects',
     $this->translate('Restrict access to the objects that match the filter')
diff --git a/library/Notifications/Model/Channel.php b/library/Notifications/Model/Channel.php
index cc4f8103..c7ad1f16 100644
--- a/library/Notifications/Model/Channel.php
+++ b/library/Notifications/Model/Channel.php
@@ -46,7 +46,8 @@ public function getColumns(): array
             'type',
             'config',
             'changed_at',
-            'deleted'
+            'deleted',
+            'external_uuid'
         ];
     }
 
@@ -55,7 +56,7 @@ public function getColumnDefinitions(): array
         return [
             'name'          => t('Name'),
             'type'          => t('Type'),
-            'changed_at'    => t('Changed At')
+            'external_uuid' => t('UUID')
         ];
     }
 
diff --git a/library/Notifications/Model/Contact.php b/library/Notifications/Model/Contact.php
index 10f17b01..629aad1c 100644
--- a/library/Notifications/Model/Contact.php
+++ b/library/Notifications/Model/Contact.php
@@ -50,7 +50,8 @@ public function getColumns(): array
             'username',
             'default_channel_id',
             'changed_at',
-            'deleted'
+            'deleted',
+            'external_uuid'
         ];
     }
 
@@ -59,7 +60,7 @@ public function getColumnDefinitions(): array
         return [
             'full_name'     => t('Full Name'),
             'username'      => t('Username'),
-            'changed_at'    => t('Changed At')
+            'external_uuid' => t('UUID')
         ];
     }
 
diff --git a/library/Notifications/Model/Contactgroup.php b/library/Notifications/Model/Contactgroup.php
index 3dc79481..95595cd0 100644
--- a/library/Notifications/Model/Contactgroup.php
+++ b/library/Notifications/Model/Contactgroup.php
@@ -42,13 +42,17 @@ public function getColumns(): array
         return [
             'name',
             'changed_at',
-            'deleted'
+            'deleted',
+            'external_uuid'
         ];
     }
 
     public function getColumnDefinitions(): array
     {
-        return ['name' => t('Name')];
+        return [
+            'name'          => t('Name'),
+            'external_uuid' => t('UUID')
+        ];
     }
 
     public function getSearchColumns(): array
diff --git a/library/Notifications/Web/Control/SearchBar/ObjectSuggestions.php b/library/Notifications/Web/Control/SearchBar/ObjectSuggestions.php
index 6ca9b208..956bd378 100644
--- a/library/Notifications/Web/Control/SearchBar/ObjectSuggestions.php
+++ b/library/Notifications/Web/Control/SearchBar/ObjectSuggestions.php
@@ -231,7 +231,7 @@ protected function queryTags(Model $model, string $searchTerm): Query
 
     protected function matchSuggestion($path, $label, $searchTerm)
     {
-        if (preg_match('/[_.](id)$/', $path)) {
+        if (preg_match('/[_.](id|uuid)$/', $path)) {
             // Only suggest exotic columns if the user knows about them
             $trimmedSearch = trim($searchTerm, ' *');
             return substr($path, -strlen($trimmedSearch)) === $trimmedSearch;
diff --git a/library/Notifications/Web/Form/ContactForm.php b/library/Notifications/Web/Form/ContactForm.php
index 246f015a..70ebfae2 100644
--- a/library/Notifications/Web/Form/ContactForm.php
+++ b/library/Notifications/Web/Form/ContactForm.php
@@ -21,6 +21,7 @@
 use ipl\Validator\StringLengthValidator;
 use ipl\Web\Common\CsrfCounterMeasure;
 use ipl\Web\Compat\CompatForm;
+use Ramsey\Uuid\Uuid;
 
 class ContactForm extends CompatForm
 {
@@ -185,7 +186,11 @@ public function addContact(): void
         $contactInfo = $this->getValues();
         $changedAt = time() * 1000;
         $this->db->beginTransaction();
-        $this->db->insert('contact', $contactInfo['contact'] + ['changed_at' => $changedAt]);
+        $this->db->insert(
+            'contact',
+            $contactInfo['contact'] + ['external_uuid' => Uuid::uuid4()->toString(), 'changed_at' => $changedAt]
+        );
+
         $this->contactId = $this->db->lastInsertId();
 
         foreach (array_filter($contactInfo['contact_address']) as $type => $address) {
diff --git a/phpstan-baseline-7x.neon b/phpstan-baseline-7x.neon
index 5be0f381..5c9adab6 100644
--- a/phpstan-baseline-7x.neon
+++ b/phpstan-baseline-7x.neon
@@ -1,10 +1,5 @@
 parameters:
 	ignoreErrors:
-		-
-			message: "#^Parameter \\#2 \\$str of function explode expects string, mixed given\\.$#"
-			count: 2
-			path: application/forms/EntryForm.php
-
 		-
 			message: "#^Parameter \\#2 \\$str of function explode expects string, mixed given\\.$#"
 			count: 2
diff --git a/phpstan-baseline-8x.neon b/phpstan-baseline-8x.neon
index 99ed68cf..a26c7dd5 100644
--- a/phpstan-baseline-8x.neon
+++ b/phpstan-baseline-8x.neon
@@ -1,10 +1,5 @@
 parameters:
 	ignoreErrors:
-		-
-			message: "#^Parameter \\#2 \\$string of function explode expects string, mixed given\\.$#"
-			count: 2
-			path: application/forms/EntryForm.php
-
 		-
 			message: "#^Parameter \\#2 \\$string of function explode expects string, mixed given\\.$#"
 			count: 2
diff --git a/phpstan-baseline-standard.neon b/phpstan-baseline-standard.neon
index 7c04a796..2009dc0b 100644
--- a/phpstan-baseline-standard.neon
+++ b/phpstan-baseline-standard.neon
@@ -45,11 +45,6 @@ parameters:
 			count: 1
 			path: application/controllers/ChannelsController.php
 
-		-
-			message: "#^Parameter \\#1 \\$name of method ipl\\\\Web\\\\Widget\\\\Tabs\\:\\:add\\(\\) expects string, mixed given\\.$#"
-			count: 1
-			path: application/controllers/ChannelsController.php
-
 		-
 			message: "#^Parameter \\#2 \\.\\.\\.\\$values of function sprintf expects bool\\|float\\|int\\|string\\|null, mixed given\\.$#"
 			count: 1
@@ -60,11 +55,6 @@ parameters:
 			count: 1
 			path: application/controllers/ConfigController.php
 
-		-
-			message: "#^Parameter \\#1 \\$name of method ipl\\\\Web\\\\Widget\\\\Tabs\\:\\:add\\(\\) expects string, mixed given\\.$#"
-			count: 1
-			path: application/controllers/ConfigController.php
-
 		-
 			message: "#^Cannot access property \\$full_name on ipl\\\\Orm\\\\Model\\|null\\.$#"
 			count: 1
@@ -120,11 +110,6 @@ parameters:
 			count: 2
 			path: application/controllers/EventRuleController.php
 
-		-
-			message: "#^Cannot access property \\$rule_escalation on ipl\\\\Orm\\\\Model\\|null\\.$#"
-			count: 1
-			path: application/controllers/EventRuleController.php
-
 		-
 			message: "#^Cannot access property \\$rule_escalation_recipient on mixed\\.$#"
 			count: 1
@@ -275,161 +260,6 @@ parameters:
 			count: 1
 			path: application/forms/DatabaseConfigForm.php
 
-		-
-			message: "#^Call to an undefined method ipl\\\\Html\\\\Contract\\\\FormElement\\:\\:isChecked\\(\\)\\.$#"
-			count: 1
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Call to an undefined method ipl\\\\Html\\\\Contract\\\\FormElement\\:\\:prepareMultipartUpdate\\(\\)\\.$#"
-			count: 2
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Call to an undefined method ipl\\\\Html\\\\Contract\\\\FormElement\\:\\:setDescription\\(\\)\\.$#"
-			count: 3
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Call to an undefined method ipl\\\\Html\\\\Contract\\\\FormElement\\:\\:setLabel\\(\\)\\.$#"
-			count: 1
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Call to an undefined method ipl\\\\Scheduler\\\\RRule\\:\\:getUntil\\(\\)\\.$#"
-			count: 1
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Call to an undefined method ipl\\\\Sql\\\\Connection\\:\\:lastInsertId\\(\\)\\.$#"
-			count: 1
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Cannot access offset 'frequency' on mixed\\.$#"
-			count: 1
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Cannot access offset 'rrule' on mixed\\.$#"
-			count: 1
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Cannot access offset 'start' on mixed\\.$#"
-			count: 1
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Cannot access property \\$contact_id on mixed\\.$#"
-			count: 6
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Cannot access property \\$contactgroup_id on mixed\\.$#"
-			count: 4
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Cannot access property \\$full_name on mixed\\.$#"
-			count: 1
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Cannot access property \\$id on mixed\\.$#"
-			count: 2
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Cannot access property \\$name on mixed\\.$#"
-			count: 1
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Cannot call method add\\(\\) on DateTime\\|false\\.$#"
-			count: 1
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Cannot call method diff\\(\\) on mixed\\.$#"
-			count: 1
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Cannot call method format\\(\\) on DateTime\\|false\\.$#"
-			count: 1
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Cannot call method format\\(\\) on mixed\\.$#"
-			count: 2
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Cannot call method getTimezone\\(\\) on DateTime\\|false\\.$#"
-			count: 1
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Cannot cast mixed to int\\.$#"
-			count: 2
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Cannot clone non\\-object variable \\$start of type DateTime\\|false\\.$#"
-			count: 1
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Forms\\\\EntryForm\\:\\:assemble\\(\\) has no return type specified\\.$#"
-			count: 1
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Forms\\\\EntryForm\\:\\:formValuesToDb\\(\\) return type has no value type specified in iterable type array\\.$#"
-			count: 1
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Forms\\\\EntryForm\\:\\:getPartUpdates\\(\\) return type has no value type specified in iterable type array\\.$#"
-			count: 1
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Method class@anonymous/application/forms/EntryForm\\.php\\:142\\:\\:assemble\\(\\) has no return type specified\\.$#"
-			count: 1
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Method ipl\\\\Html\\\\Contract\\\\FormElement\\:\\:getValue\\(\\) invoked with 1 parameter, 0 required\\.$#"
-			count: 1
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Parameter \\#1 \\$json of static method ipl\\\\Scheduler\\\\RRule\\:\\:fromJson\\(\\) expects string, string\\|false given\\.$#"
-			count: 1
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Parameter \\#1 \\.\\.\\.\\$content of method ipl\\\\Html\\\\HtmlDocument\\:\\:setHtmlContent\\(\\) expects ipl\\\\Html\\\\ValidHtml, ipl\\\\Html\\\\Contract\\\\Wrappable\\|null given\\.$#"
-			count: 1
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Parameter \\#2 \\$datetime of static method DateTime\\:\\:createFromFormat\\(\\) expects string, mixed given\\.$#"
-			count: 2
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Parameter \\#2 \\$value of static method ipl\\\\Stdlib\\\\Filter\\:\\:equal\\(\\) expects array\\|bool\\|float\\|int\\|string, mixed given\\.$#"
-			count: 1
-			path: application/forms/EntryForm.php
-
-		-
-			message: "#^Property Icinga\\\\Module\\\\Notifications\\\\Forms\\\\EntryForm\\:\\:\\$submitLabel \\(string\\) on left side of \\?\\? is not nullable\\.$#"
-			count: 1
-			path: application/forms/EntryForm.php
-
 		-
 			message: "#^Call to an undefined method ipl\\\\Html\\\\Contract\\\\FormElement\\:\\:setName\\(\\)\\.$#"
 			count: 4
@@ -580,11 +410,6 @@ parameters:
 			count: 1
 			path: application/forms/ScheduleForm.php
 
-		-
-			message: "#^Cannot access property \\$id on mixed\\.$#"
-			count: 3
-			path: application/forms/ScheduleForm.php
-
 		-
 			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Forms\\\\ScheduleForm\\:\\:assemble\\(\\) has no return type specified\\.$#"
 			count: 1
@@ -675,11 +500,6 @@ parameters:
 			count: 1
 			path: library/Notifications/Model/ContactAddress.php
 
-		-
-			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Model\\\\Contactgroup\\:\\:createRelations\\(\\) has no return type specified\\.$#"
-			count: 1
-			path: library/Notifications/Model/Contactgroup.php
-
 		-
 			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Model\\\\Event\\:\\:createBehaviors\\(\\) has no return type specified\\.$#"
 			count: 1
@@ -840,11 +660,6 @@ parameters:
 			count: 1
 			path: library/Notifications/Model/RuleEscalationRecipient.php
 
-		-
-			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Model\\\\ScheduleMember\\:\\:createRelations\\(\\) has no return type specified\\.$#"
-			count: 1
-			path: library/Notifications/Model/ScheduleMember.php
-
 		-
 			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Model\\\\Source\\:\\:createRelations\\(\\) has no return type specified\\.$#"
 			count: 1
@@ -1000,26 +815,11 @@ parameters:
 			count: 1
 			path: library/Notifications/Web/Form/EventRuleDecorator.php
 
-		-
-			message: "#^Call to an undefined method DateTimeInterface\\:\\:add\\(\\)\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar.php
-
-		-
-			message: "#^Cannot call method diff\\(\\) on DateTime\\|null\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar.php
-
 		-
 			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\:\\:assemble\\(\\) has no return type specified\\.$#"
 			count: 1
 			path: library/Notifications/Widget/Calendar.php
 
-		-
-			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\:\\:getEntries\\(\\) return type has no value type specified in iterable type Traversable\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar.php
-
 		-
 			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\:\\:getModeStart\\(\\) should return DateTime but returns DateTime\\|false\\.$#"
 			count: 2
@@ -1030,26 +830,6 @@ parameters:
 			count: 1
 			path: library/Notifications/Widget/Calendar.php
 
-		-
-			message: "#^Parameter \\#1 \\$from of static method Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\\\Util\\:\\:diffHours\\(\\) expects DateTime, DateTime\\|null given\\.$#"
-			count: 2
-			path: library/Notifications/Widget/Calendar.php
-
-		-
-			message: "#^Parameter \\#1 \\$start of method Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\\\Entry\\:\\:setStart\\(\\) expects DateTime, DateTimeInterface given\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar.php
-
-		-
-			message: "#^Parameter \\#1 \\$start of method ipl\\\\Scheduler\\\\RRule\\:\\:startAt\\(\\) expects DateTimeInterface, DateTime\\|null given\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar.php
-
-		-
-			message: "#^Parameter \\#2 \\$to of static method Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\\\Util\\:\\:diffHours\\(\\) expects DateTime, DateTime\\|null given\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar.php
-
 		-
 			message: "#^Property Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\:\\:\\$addEntryUrl \\(ipl\\\\Web\\\\Url\\) does not accept ipl\\\\Web\\\\Url\\|null\\.$#"
 			count: 1
@@ -1060,31 +840,6 @@ parameters:
 			count: 1
 			path: library/Notifications/Widget/Calendar/Attendee.php
 
-		-
-			message: "#^Cannot call method format\\(\\) on DateTime\\|null\\.$#"
-			count: 7
-			path: library/Notifications/Widget/Calendar/BaseGrid.php
-
-		-
-			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\\\BaseGrid\\:\\:createGridSteps\\(\\) return type has no value type specified in iterable type Traversable\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar/BaseGrid.php
-
-		-
-			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\\\BaseGrid\\:\\:getGridArea\\(\\) return type has no value type specified in iterable type array\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar/BaseGrid.php
-
-		-
-			message: "#^Parameter \\#1 \\$content of static method ipl\\\\Html\\\\Text\\:\\:create\\(\\) expects string, string\\|null given\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar/BaseGrid.php
-
-		-
-			message: "#^Property Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\\\BaseGrid\\:\\:\\$extraEntriesCount type has no value type specified in iterable type array\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar/BaseGrid.php
-
 		-
 			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\\\Controls\\:\\:assemble\\(\\) has no return type specified\\.$#"
 			count: 1
@@ -1100,91 +855,16 @@ parameters:
 			count: 1
 			path: library/Notifications/Widget/Calendar/DayGrid.php
 
-		-
-			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\\\DayGrid\\:\\:createGridSteps\\(\\) return type has no value type specified in iterable type Traversable\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar/DayGrid.php
-
-		-
-			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\\\DayGrid\\:\\:getGridArea\\(\\) return type has no value type specified in iterable type array\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar/DayGrid.php
-
-		-
-			message: "#^Property Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\\\Entry\\:\\:\\$description has no type specified\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar/Entry.php
-
-		-
-			message: "#^Property Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\\\Entry\\:\\:\\$end has no type specified\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar/Entry.php
-
-		-
-			message: "#^Property Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\\\Entry\\:\\:\\$id has no type specified\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar/Entry.php
-
-		-
-			message: "#^Property Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\\\Entry\\:\\:\\$isOccurrence has no type specified\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar/Entry.php
-
-		-
-			message: "#^Property Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\\\Entry\\:\\:\\$rrule has no type specified\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar/Entry.php
-
-		-
-			message: "#^Property Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\\\Entry\\:\\:\\$start has no type specified\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar/Entry.php
-
-		-
-			message: "#^Property Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\\\Entry\\:\\:\\$url \\(ipl\\\\Web\\\\Url\\) does not accept ipl\\\\Web\\\\Url\\|null\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar/Entry.php
-
-		-
-			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\\\ExtraEntryCount\\:\\:assemble\\(\\) has no return type specified\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar/ExtraEntryCount.php
-
 		-
 			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\\\MonthGrid\\:\\:assemble\\(\\) has no return type specified\\.$#"
 			count: 1
 			path: library/Notifications/Widget/Calendar/MonthGrid.php
 
-		-
-			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\\\MonthGrid\\:\\:createGridSteps\\(\\) return type has no value type specified in iterable type Traversable\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar/MonthGrid.php
-
-		-
-			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\\\MonthGrid\\:\\:getGridArea\\(\\) return type has no value type specified in iterable type array\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar/MonthGrid.php
-
-		-
-			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\\\Util\\:\\:diffHours\\(\\) has no return type specified\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar/Util.php
-
 		-
 			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\\\WeekGrid\\:\\:assemble\\(\\) has no return type specified\\.$#"
 			count: 1
 			path: library/Notifications/Widget/Calendar/WeekGrid.php
 
-		-
-			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\\\WeekGrid\\:\\:createGridSteps\\(\\) return type has no value type specified in iterable type Traversable\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar/WeekGrid.php
-
-		-
-			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Calendar\\\\WeekGrid\\:\\:getGridArea\\(\\) return type has no value type specified in iterable type array\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Calendar/WeekGrid.php
-
 		-
 			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Widget\\\\CheckboxIcon\\:\\:assemble\\(\\) has no return type specified\\.$#"
 			count: 1
@@ -1410,11 +1090,6 @@ parameters:
 			count: 2
 			path: library/Notifications/Widget/RecipientSuggestions.php
 
-		-
-			message: "#^Cannot access property \\$color on mixed\\.$#"
-			count: 2
-			path: library/Notifications/Widget/RecipientSuggestions.php
-
 		-
 			message: "#^Cannot access property \\$full_name on mixed\\.$#"
 			count: 2
@@ -1480,66 +1155,11 @@ parameters:
 			count: 1
 			path: library/Notifications/Widget/RuleEscalationRecipientBadge.php
 
-		-
-			message: "#^Cannot access property \\$contact on mixed\\.$#"
-			count: 2
-			path: library/Notifications/Widget/Schedule.php
-
-		-
-			message: "#^Cannot access property \\$contact_id on mixed\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Schedule.php
-
-		-
-			message: "#^Cannot access property \\$contactgroup on mixed\\.$#"
-			count: 2
-			path: library/Notifications/Widget/Schedule.php
-
-		-
-			message: "#^Cannot access property \\$description on mixed\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Schedule.php
-
-		-
-			message: "#^Cannot access property \\$end_time on mixed\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Schedule.php
-
-		-
-			message: "#^Cannot access property \\$id on mixed\\.$#"
-			count: 2
-			path: library/Notifications/Widget/Schedule.php
-
-		-
-			message: "#^Cannot access property \\$rrule on mixed\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Schedule.php
-
-		-
-			message: "#^Cannot access property \\$start_time on mixed\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Schedule.php
-
-		-
-			message: "#^Cannot access property \\$timeperiod_id on mixed\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Schedule.php
-
-		-
-			message: "#^Cannot access property \\$timezone on mixed\\.$#"
-			count: 2
-			path: library/Notifications/Widget/Schedule.php
-
 		-
 			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Schedule\\:\\:assemble\\(\\) has no return type specified\\.$#"
 			count: 1
 			path: library/Notifications/Widget/Schedule.php
 
-		-
-			message: "#^Property Icinga\\\\Module\\\\Notifications\\\\Widget\\\\Schedule\\:\\:\\$schedule \\(Icinga\\\\Module\\\\Notifications\\\\Model\\\\Schedule\\) does not accept Icinga\\\\Module\\\\Notifications\\\\Model\\\\Schedule\\|null\\.$#"
-			count: 1
-			path: library/Notifications/Widget/Schedule.php
-
 		-
 			message: "#^Method Icinga\\\\Module\\\\Notifications\\\\Widget\\\\ShowMore\\:\\:assemble\\(\\) has no return type specified\\.$#"
 			count: 1
diff --git a/run.php b/run.php
index 9e94cef8..fd185e72 100644
--- a/run.php
+++ b/run.php
@@ -21,3 +21,42 @@
         ]
     )
 );
+
+$this->addRoute('notifications/api-v1-contacts', new Zend_Controller_Router_Route_Regex(
+    'notifications/api/v1/contacts(?:\/(.+)|\?(.+))?',
+    [
+        'controller'    => 'api-v1-contacts',
+        'action'        => 'index',
+        'module'        => 'notifications',
+        'identifier'    => null
+    ],
+    [
+        1 => 'identifier'
+    ]
+));
+
+$this->addRoute('notifications/api-v1-contactgroups', new Zend_Controller_Router_Route_Regex(
+    'notifications/api/v1/contactgroups(?:\/(.+)|\?(.+))?',
+    [
+        'controller'    => 'api-v1-contactgroups',
+        'action'        => 'index',
+        'module'        => 'notifications',
+        'identifier'    => null
+    ],
+    [
+        1 => 'identifier'
+    ]
+));
+
+$this->addRoute('notifications/api-v1-channels', new Zend_Controller_Router_Route_Regex(
+    'notifications/api/v1/channels(?:\/(.+)|\?(.+))?',
+    [
+        'controller'    => 'api-v1-channels',
+        'action'        => 'index',
+        'module'        => 'notifications',
+        'identifier'    => null
+    ],
+    [
+        1 => 'identifier'
+    ]
+));