diff --git a/appinfo/routes.php b/appinfo/routes.php
index b05194360..93fa5662a 100644
--- a/appinfo/routes.php
+++ b/appinfo/routes.php
@@ -39,6 +39,8 @@
 		['name' => 'contact#searchPhoto', 'url' => '/v1/autocompletion/photo', 'verb' => 'POST'],
 		// Circles
 		['name' => 'contact#getCircleMembers', 'url' => '/v1/circles/getmembers', 'verb' => 'GET'],
+		// Contact Groups
+		['name' => 'contact#getContactGroupMembers', 'url' => '/v1/autocompletion/groupmembers', 'verb' => 'POST'],
 		// Settings
 		['name' => 'settings#setConfig', 'url' => '/v1/config/{key}', 'verb' => 'POST'],
 		// Tools
diff --git a/lib/Controller/ContactController.php b/lib/Controller/ContactController.php
index af1ee7518..702258696 100644
--- a/lib/Controller/ContactController.php
+++ b/lib/Controller/ContactController.php
@@ -7,11 +7,14 @@
  */
 namespace OCA\Calendar\Controller;
 
+use Exception;
+use OCA\Calendar\Service\ContactsService;
 use OCA\Calendar\Service\ServiceException;
 use OCA\Circles\Exceptions\CircleNotFoundException;
 use OCP\App\IAppManager;
 use OCP\AppFramework\Controller;
 use OCP\AppFramework\Http;
+use OCP\AppFramework\Http\Attribute\NoAdminRequired;
 use OCP\AppFramework\Http\JSONResponse;
 use OCP\AppFramework\QueryException;
 use OCP\Contacts\IManager;
@@ -24,31 +27,21 @@
  * @package OCA\Calendar\Controller
  */
 class ContactController extends Controller {
-	/** @var IManager */
-	private $contactsManager;
-
-	/** @var IAppManager */
-	private $appManager;
-
-	/** @var IUserManager */
-	private $userManager;
-
 	/**
 	 * ContactController constructor.
 	 *
 	 * @param string $appName
 	 * @param IRequest $request
-	 * @param IManager $contacts
 	 */
-	public function __construct(string $appName,
+	public function __construct(
+		string $appName,
 		IRequest $request,
-		IManager $contacts,
-		IAppManager $appManager,
-		IUserManager $userManager) {
+		private IManager $contactsManager,
+		private IAppManager $appManager,
+		private IUserManager $userManager,
+		private ContactsService $contactsService,
+	) {
 		parent::__construct($appName, $request);
-		$this->contactsManager = $contacts;
-		$this->appManager = $appManager;
-		$this->userManager = $userManager;
 	}
 
 	/**
@@ -59,7 +52,7 @@ public function __construct(string $appName,
 	 *
 	 * @NoAdminRequired
 	 */
-	public function searchLocation(string $search):JSONResponse {
+	public function searchLocation(string $search): JSONResponse {
 		if (!$this->contactsManager->isEnabled()) {
 			return new JSONResponse();
 		}
@@ -69,7 +62,7 @@ public function searchLocation(string $search):JSONResponse {
 		$contacts = [];
 		foreach ($result as $r) {
 			// Information about system users is fetched via DAV nowadays
-			if (isset($r['isLocalSystemBook']) && $r['isLocalSystemBook']) {
+			if ($this->contactsService->isSystemBook($r)) {
 				continue;
 			}
 
@@ -77,19 +70,9 @@ public function searchLocation(string $search):JSONResponse {
 				continue;
 			}
 
-			$name = $this->getNameFromContact($r);
-			if (\is_string($r['ADR'])) {
-				$r['ADR'] = [$r['ADR']];
-			}
-
-			$photo = isset($r['PHOTO'])
-				? $this->getPhotoUri($r['PHOTO'])
-				: null;
-
-			$addresses = [];
-			foreach ($r['ADR'] as $address) {
-				$addresses[] = trim(preg_replace("/\n+/", "\n", str_replace(';', "\n", $address)));
-			}
+			$name = $this->contactsService->getNameFromContact($r);
+			$photo = $this->contactsService->getPhotoUri($r);
+			$addresses = $this->contactsService->getAddress($r);
 
 			$contacts[] = [
 				'name' => $name,
@@ -119,51 +102,78 @@ public function searchAttendee(string $search):JSONResponse {
 
 		$contacts = [];
 		foreach ($result as $r) {
-			// Information about system users is fetched via DAV nowadays
-			if (isset($r['isLocalSystemBook']) && $r['isLocalSystemBook']) {
+			if ($this->contactsService->isSystemBook($r) || !$this->contactsService->hasEmail($r)) {
 				continue;
 			}
-
-			if (!isset($r['EMAIL'])) {
+			$name = $this->contactsService->getNameFromContact($r);
+			$email = $this->contactsService->getEmail($r);
+			$photo = $this->contactsService->getPhotoUri($r);
+			$timezoneId = $this->contactsService->getTimezoneId($r);
+			$lang = $this->contactsService->getLanguageId($r);
+			$contacts[] = [
+				'name' => $name,
+				'emails' => $email,
+				'lang' => $lang,
+				'tzid' => $timezoneId,
+				'photo' => $photo,
+				'type' => 'individual'
+			];
+		}
+		
+		$groups = $this->contactsManager->search($search, ['CATEGORIES']);
+		$groups = array_filter($groups, function ($group) {
+			return $this->contactsService->hasEmail($group);
+		});
+		$filtered = $this->contactsService->filterGroupsWithCount($groups, $search);
+		foreach ($filtered as $groupName => $count) {
+			if ($count === 0) {
 				continue;
 			}
+			$contacts[] = [
+				'name' => $groupName,
+				'emails' => ['mailto:group+' . urlencode($groupName) . '@group'],
+				'lang' => '',
+				'tzid' => '',
+				'photo' => '',
+				'type' => 'contactsgroup',
+				'members' => $count,
+			];
+		}
 
-			$name = $this->getNameFromContact($r);
-			if (\is_string($r['EMAIL'])) {
-				$r['EMAIL'] = [$r['EMAIL']];
-			}
+		return new JSONResponse($contacts);
+	}
 
-			$photo = isset($r['PHOTO'])
-				? $this->getPhotoUri($r['PHOTO'])
-				: null;
+	#[NoAdminRequired]
+	public function getContactGroupMembers(string $groupName): JSONResponse {
+		if (!$this->contactsManager->isEnabled()) {
+			return new JSONResponse();
+		}
 
-			$lang = null;
-			if (isset($r['LANG'])) {
-				if (\is_array($r['LANG'])) {
-					$lang = $r['LANG'][0];
-				} else {
-					$lang = $r['LANG'];
-				}
+		$groupmembers = $this->contactsManager->search($groupName, ['CATEGORIES']);
+		$contacts = [];
+		foreach ($groupmembers as $r) {
+			if (!in_array($groupName, explode(',', $r['CATEGORIES']), true)) {
+				continue;
 			}
-
-			$timezoneId = null;
-			if (isset($r['TZ'])) {
-				if (\is_array($r['TZ'])) {
-					$timezoneId = $r['TZ'][0];
-				} else {
-					$timezoneId = $r['TZ'];
-				}
+			if (!$this->contactsService->hasEmail($r) || $this->contactsService->isSystemBook($r)) {
+				continue;
 			}
-
+			$name = $this->contactsService->getNameFromContact($r);
+			$email = $this->contactsService->getEmail($r);
+			$photo = $this->contactsService->getPhotoUri($r);
+			$timezoneId = $this->contactsService->getTimezoneId($r);
+			$lang = $this->contactsService->getLanguageId($r);
 			$contacts[] = [
-				'name' => $name,
-				'emails' => $r['EMAIL'],
-				'lang' => $lang,
-				'tzid' => $timezoneId,
-				'photo' => $photo,
+				'commonName' => $name,
+				'email' => $email[0],
+				'calendarUserType' => 'INDIVIDUAL',
+				'language' => $lang,
+				'timezoneId' => $timezoneId,
+				'avatar' => $photo,
+				'isUser' => false,
+				'member' => 'mailto:group+' . urlencode($groupName) . '@group',
 			];
 		}
-
 		return new JSONResponse($contacts);
 	}
 
@@ -243,17 +253,14 @@ public function searchPhoto(string $search):JSONResponse {
 		$result = $this->contactsManager->search($search, ['EMAIL']);
 
 		foreach ($result as $r) {
-			if (!isset($r['EMAIL'])) {
+			if (!$this->contactsService->hasEmail($r) || $this->contactsService->isSystemBook($r)) {
 				continue;
 			}
-
-			if (\is_string($r['EMAIL'])) {
-				$r['EMAIL'] = [$r['EMAIL']];
-			}
+			$email = $this->contactsService->getEmail($r);
 
 			$match = false;
-			foreach ($r['EMAIL'] as $email) {
-				if ($email === $search) {
+			foreach ($email as $e) {
+				if ($e === $search) {
 					$match = true;
 				}
 			}
@@ -262,15 +269,12 @@ public function searchPhoto(string $search):JSONResponse {
 				continue;
 			}
 
-			if (!isset($r['PHOTO'])) {
+			$photo = $this->contactsService->getPhotoUri($r);
+			if ($photo === null) {
 				continue;
 			}
 
-			$name = $this->getNameFromContact($r);
-			$photo = $this->getPhotoUri($r['PHOTO']);
-			if (!$photo) {
-				continue;
-			}
+			$name = $this->contactsService->getNameFromContact($r);
 
 			return new JSONResponse([
 				'name' => $name,
@@ -281,28 +285,4 @@ public function searchPhoto(string $search):JSONResponse {
 		return new JSONResponse([], Http::STATUS_NOT_FOUND);
 	}
 
-	/**
-	 * Extract name from an array containing a contact's information
-	 *
-	 * @param array $r
-	 * @return string
-	 */
-	private function getNameFromContact(array $r):string {
-		return $r['FN'] ?? '';
-	}
-
-	/**
-	 * Get photo uri from contact
-	 *
-	 * @param string $raw
-	 * @return string|null
-	 */
-	private function getPhotoUri(string $raw):?string {
-		$uriPrefix = 'VALUE=uri:';
-		if (substr($raw, 0, strlen($uriPrefix)) === $uriPrefix) {
-			return substr($raw, strpos($raw, 'http'));
-		}
-
-		return null;
-	}
 }
diff --git a/lib/Service/ContactsService.php b/lib/Service/ContactsService.php
new file mode 100644
index 000000000..2d35e3b54
--- /dev/null
+++ b/lib/Service/ContactsService.php
@@ -0,0 +1,144 @@
+<?php
+
+declare(strict_types=1);
+/**
+ * SPDX-FileCopyrightText: 2014 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+namespace OCA\Calendar\Service;
+
+class ContactsService {
+
+
+	/**
+	 * @param array $contact
+	 * @return bool
+	 */
+	public function isSystemBook(array $contact): bool {
+		// Information about system users is fetched via DAV nowadays
+		return (isset($contact['isLocalSystemBook']) && $contact['isLocalSystemBook'] === true);
+	}
+
+	/**
+	 * @param array $contact
+	 * @return bool
+	 */
+	public function hasEmail(array $contact): bool {
+		if (!isset($contact['EMAIL'])) {
+			return false;
+		}
+
+		if (!is_array($contact['EMAIL']) && !empty($contact['EMAIL'])) {
+			return true;
+		}
+
+		if (!empty($contact['EMAIL'][0])) {
+			return true;
+		}
+
+		return false;
+	}
+
+	/**
+	 * Extract name from an array containing a contact's information
+	 *
+	 * @param array $contact
+	 * @return string
+	 */
+	public function getNameFromContact(array $contact): string {
+		return $contact['FN'] ?? '';
+	}
+
+	/**
+	 * Get photo uri from contact
+	 *
+	 * @param array $contact
+	 * @return string|null
+	 */
+	public function getPhotoUri(array $contact): ?string {
+		if (!isset($contact['PHOTO'])) {
+			return null;
+		}
+
+		$raw = $contact['PHOTO'];
+		$uriPrefix = 'VALUE=uri:';
+		if (str_starts_with($raw, $uriPrefix)) {
+			$strpos = strpos($raw, 'http');
+			return $strpos !== false ? substr($raw, $strpos) : null;
+		}
+
+		return null;
+	}
+
+	/**
+	 * @param array $contact
+	 * @return string[]
+	 */
+	public function getEmail(array $contact): array {
+		if (\is_string($contact['EMAIL'])) {
+			return [$contact['EMAIL']];
+		}
+		return $contact['EMAIL'];
+	}
+
+	/**
+	 * @param array $contact
+	 * @return string|null
+	 */
+	public function getTimezoneId(array $contact): ?string {
+		if (!isset($contact['TZ'])) {
+			return null;
+		}
+
+		if (\is_array($contact['TZ'])) {
+			return $contact['TZ'][0];
+		}
+		return $contact['TZ'];
+	}
+
+	/**
+	 * @param array $contact
+	 * @return string|null
+	 */
+	public function getLanguageId(array $contact): ?string {
+		if (!isset($contact['LANG'])) {
+			return null;
+		}
+
+		if (\is_array($contact['LANG'])) {
+			return $contact['LANG'][0];
+		}
+		return $contact['LANG'];
+	}
+
+	/**
+	 * @param array $groups
+	 * @param string $search
+	 * @return array
+	 */
+	public function filterGroupsWithCount(array $groups, string $search): array {
+		//filter to be unique
+		$categories = [];
+		foreach ($groups as $group) {
+			$categories[] = array_filter(explode(',', $group['CATEGORIES']), static function ($cat) use ($search) {
+				return str_contains(strtolower($cat), strtolower($search));
+			});
+		}
+		return array_count_values(array_merge(...$categories));
+	}
+
+	/**
+	 * @param array $contact
+	 * @return array
+	 */
+	public function getAddress(array $contact): array {
+		if (\is_string($contact['ADR'])) {
+			$contact['ADR'] = [$contact['ADR']];
+		}
+		$addresses = [];
+		foreach ($contact['ADR'] as $address) {
+			$addresses[] = trim(preg_replace("/\n+/", "\n", str_replace(';', "\n", $address)));
+		}
+		return $addresses;
+	}
+}
diff --git a/src/components/Editor/Invitees/InviteesListSearch.vue b/src/components/Editor/Invitees/InviteesListSearch.vue
index a27b5ff02..2f2a73d86 100644
--- a/src/components/Editor/Invitees/InviteesListSearch.vue
+++ b/src/components/Editor/Invitees/InviteesListSearch.vue
@@ -37,10 +37,10 @@
 					<div>
 						{{ option.commonName }}
 					</div>
-					<div v-if="option.email !== option.commonName && option.type !== 'circle'">
+					<div v-if="option.email !== option.commonName && option.type !== 'circle' && option.type !== 'contactsgroup'">
 						{{ option.email }}
 					</div>
-					<div v-if="option.type === 'circle'">
+					<div v-if="option.type === 'circle' || option.type === 'contactsgroup'">
 						{{ option.subtitle }}
 					</div>
 				</div>
@@ -161,6 +161,21 @@ export default {
 				showInfo(this.$t('calendar', 'Note that members of circles get invited but are not synced yet.'))
 				this.resolveCircleMembers(selectedValue.id, selectedValue.email)
 			}
+			if (selectedValue.type === 'contactsgroup') {
+				showInfo(this.$t('calendar', 'Note that members of contact groups get invited but are not synced yet.'))
+				this.getContactGroupMembers(selectedValue.commonName)
+				let group = {
+					calendarUserType: 'GROUP',
+					commonName: selectedValue.commonName,
+					dropdownName: selectedValue.dropdownName,
+					email: selectedValue.email,
+					isUser: false,
+					subtitle: selectedValue.subtitle,
+					type: 'contactsgroup',
+				}
+				this.$emit('add-attendee', group)
+				return
+			}
 			this.$emit('add-attendee', selectedValue)
 		},
 		async resolveCircleMembers(circleId, groupId) {
@@ -180,6 +195,23 @@ export default {
 				}
 			})
 		},
+		async getContactGroupMembers(groupName) {
+			let results
+			try {
+				results = await HttpClient.post(linkTo('calendar', 'index.php') + '/v1/autocompletion/groupmembers', {
+					groupName,
+				})
+			} catch (error) {
+				console.debug(error)
+				return []
+			}
+
+			results.data.forEach((member) => {
+				if (!this.organizer || member.email !== this.organizer.uri) {
+					this.$emit('add-attendee', member)
+				}
+			})
+		},
 		async findAttendeesFromContactsAPI(query) {
 			let response
 
@@ -210,6 +242,24 @@ export default {
 						return
 					}
 
+					if(result.type === 'contactsgroup') {
+						arr.push({
+							calendarUserType: 'GROUP',
+							commonName: result.name,
+							subtitle: this.$n('calendar', '%n member', '%n members', result.members),
+							members: {length: result.members},
+							email,
+							isUser: false,
+							avatar: result.photo,
+							language: result.lang,
+							timezoneId: result.tzid,
+							hasMultipleEMails: false,
+							dropdownName: name,
+							type: 'contactsgroup',
+						})
+						return
+					}
+
 					arr.push({
 						calendarUserType: 'INDIVIDUAL',
 						commonName: result.name,
@@ -246,7 +296,7 @@ export default {
 
 				// We do not support GROUPS for now
 				if (principal.calendarUserType === 'GROUP') {
-					return false
+					console.debug(principal)
 				}
 
 				// Do not include resources and rooms
diff --git a/src/views/EditSidebar.vue b/src/views/EditSidebar.vue
index ffec6df23..c0a1cb843 100644
--- a/src/views/EditSidebar.vue
+++ b/src/views/EditSidebar.vue
@@ -522,7 +522,6 @@ export default {
 				this.showPreloader = true
 				if (!this.isPrivate()) {
 					this.showModalNewAttachments.map(async (attachment, i) => {
-						// console.log('Add share', attachment)
 						this.sharedProgress = Math.ceil(100 * (i + 1) / total)
 
 						// add share + change attachment
diff --git a/tests/php/unit/Controller/ContactControllerTest.php b/tests/php/unit/Controller/ContactControllerTest.php
index 3b176ee3c..afba3dfb7 100644
--- a/tests/php/unit/Controller/ContactControllerTest.php
+++ b/tests/php/unit/Controller/ContactControllerTest.php
@@ -8,6 +8,7 @@
 namespace OCA\Calendar\Controller;
 
 use ChristophWurst\Nextcloud\Testing\TestCase;
+use OCA\Calendar\Service\ContactsService;
 use OCP\App\IAppManager;
 use OCP\AppFramework\Http\JSONResponse;
 use OCP\Contacts\IManager;
@@ -30,6 +31,7 @@ class ContactControllerTest extends TestCase {
 
 	/** @var IUserManager|MockObject */
 	private $userManager;
+	private ContactsService|MockObject $service;
 
 	/** @var ContactController */
 	protected $controller;
@@ -42,17 +44,22 @@ protected function setUp():void {
 		$this->manager = $this->createMock(IManager::class);
 		$this->appManager = $this->createMock(IAppManager::class);
 		$this->userManager = $this->createMock(IUserManager::class);
+		$this->service = $this->createMock(ContactsService::class);
 		$this->controller = new ContactController($this->appName,
-			$this->request, $this->manager, $this->appManager, $this->userManager);
+			$this->request,
+			$this->manager,
+			$this->appManager,
+			$this->userManager,
+			$this->service
+		);
 	}
 
 	public function testSearchLocationDisabled():void {
-		$this->manager->expects($this->once())
+		$this->manager->expects(self::once())
 			->method('isEnabled')
-			->with()
 			->willReturn(false);
 
-		$this->manager->expects($this->never())
+		$this->manager->expects(self::never())
 			->method('search');
 
 		$response = $this->controller->searchLocation('search 123');
@@ -63,57 +70,89 @@ public function testSearchLocationDisabled():void {
 	}
 
 	public function testSearchLocation():void {
+		$user1 = [
+			'FN' => 'Person 1',
+			'ADR' => [
+				'33 42nd Street;Random Town;Some State;;United States',
+				';;5 Random Ave;12782 Some big city;Yet another state;United States',
+			],
+			'EMAIL' => [
+				'foo1@example.com',
+				'foo2@example.com',
+			],
+			'LANG' => [
+				'de',
+				'en'
+			],
+			'TZ' => [
+				'Europe/Berlin',
+				'UTC'
+			],
+			'PHOTO' => 'VALUE=uri:http://foo.bar'
+		];
+		$user2 = [
+			'FN' => 'Person 2',
+			'EMAIL' => 'foo3@example.com',
+		];
+		$user3 = [
+			'ADR' => [
+				'ABC Street 2;01337 Village;;Germany',
+			],
+			'LANG' => 'en_us',
+			'TZ' => 'Australia/Adelaide',
+			'PHOTO' => 'VALUE:BINARY:4242424242'
+		];
+		$user4 = [
+			'isLocalSystemBook' => true,
+			'FN' => 'Person 3',
+			'ADR' => [
+				'ABC Street 2;01337 Village;;Germany',
+			],
+			'LANG' => 'en_us',
+			'TZ' => 'Australia/Adelaide',
+			'PHOTO' => 'VALUE:BINARY:4242424242'
+		];
+
 		$this->manager->expects(self::once())
 			->method('isEnabled')
-			->with()
 			->willReturn(true);
-
+		$this->service
+			->method('isSystemBook')
+			->willReturnMap([
+				[$user1, false],
+				[$user2, false],
+				[$user3, false],
+				[$user4, true],
+			]);
+		$this->service
+			->method('getNameFromContact')
+			->willReturnMap([
+				[$user1, 'Person 1'],
+				[$user3, ''],
+			]);
+		$this->service->method('getPhotoUri')
+			->willReturnMap([
+				[$user1, 'http://foo.bar'],
+				[$user3, null]
+			]);
+		$this->service->method('getAddress')
+			->willReturnMap([
+				[$user1, [
+					"33 42nd Street\nRandom Town\nSome State\nUnited States",
+					"5 Random Ave\n12782 Some big city\nYet another state\nUnited States",
+				]],
+				[$user3, [
+					"ABC Street 2\n01337 Village\nGermany",
+				]],
+			]);
 		$this->manager->expects(self::once())
 			->method('search')
 			->with('search 123', ['FN', 'ADR'])
 			->willReturn([
-				[
-					'FN' => 'Person 1',
-					'ADR' => [
-						'33 42nd Street;Random Town;Some State;;United States',
-						';;5 Random Ave;12782 Some big city;Yet another state;United States',
-					],
-					'EMAIL' => [
-						'foo1@example.com',
-						'foo2@example.com',
-					],
-					'LANG' => [
-						'de',
-						'en'
-					],
-					'TZ' => [
-						'Europe/Berlin',
-						'UTC'
-					],
-					'PHOTO' => 'VALUE=uri:http://foo.bar'
-				],
-				[
-					'FN' => 'Person 2',
-					'EMAIL' => 'foo3@example.com',
-				],
-				[
-					'ADR' => [
-						'ABC Street 2;01337 Village;;Germany',
-					],
-					'LANG' => 'en_us',
-					'TZ' => 'Australia/Adelaide',
-					'PHOTO' => 'VALUE:BINARY:4242424242'
-				],
-				[
-					'isLocalSystemBook' => true,
-					'FN' => 'Person 3',
-					'ADR' => [
-						'ABC Street 2;01337 Village;;Germany',
-					],
-					'LANG' => 'en_us',
-					'TZ' => 'Australia/Adelaide',
-					'PHOTO' => 'VALUE:BINARY:4242424242'
-				],
+				$user1,
+				$user2,
+				$user3,
+				$user4,
 			]);
 
 		$response = $this->controller->searchLocation('search 123');
@@ -138,31 +177,44 @@ public function testSearchLocation():void {
 		$this->assertEquals(200, $response->getStatus());
 	}
 
-	public function testSearchAttendeeDisabled():void {
-		$this->manager->expects($this->once())
+	public function testGetGroupMembersNoResults() {
+		$this->manager->expects(self::once())
 			->method('isEnabled')
-			->with()
-			->willReturn(false);
-
-		$this->manager->expects($this->never())
-			->method('search');
+			->willReturn(true);
 
-		$response = $this->controller->searchAttendee('search 123');
+		$groupname = 'groupname';
+		$this->manager->expects(self::once())
+			->method('search')
+			->with($groupname, ['CATEGORIES'])
+			->willReturn([]);
 
-		$this->assertInstanceOf(JSONResponse::class, $response);
-		$this->assertEquals([], $response->getData());
-		$this->assertEquals(200, $response->getStatus());
+		$this->controller->getContactGroupMembers($groupname);
 	}
 
-	public function testSearchAttendee():void {
+	public function testGetGroupMembers() {
 		$this->manager->expects(self::once())
 			->method('isEnabled')
-			->with()
 			->willReturn(true);
-
+		$this->service->expects(self::once())
+			->method('hasEmail')
+			->willReturn(true);
+		$this->service->expects(self::once())
+			->method('getNameFromContact')
+			->willReturn('Person 1');
+		$this->service->expects(self::once())
+			->method('getLanguageId')
+			->willReturn('en_us');
+		$this->service->expects(self::once())
+			->method('getTimezoneId')
+			->willReturn('Australia/Adelaide');
+		$this->service->expects(self::once())
+			->method('getEmail')
+			->willReturn(['foo1@example.com']);
+
+		$groupname = 'group';
 		$this->manager->expects(self::once())
 			->method('search')
-			->with('search 123', ['FN', 'EMAIL'])
+			->with($groupname, ['CATEGORIES'])
 			->willReturn([
 				[
 					'FN' => 'Person 1',
@@ -182,11 +234,13 @@ public function testSearchAttendee():void {
 						'Europe/Berlin',
 						'UTC'
 					],
-					'PHOTO' => 'VALUE=uri:http://foo.bar'
+					'PHOTO' => 'VALUE=uri:http://foo.bar',
+					'CATEGORIES' => 'groupname,group',
 				],
 				[
 					'FN' => 'Person 2',
 					'EMAIL' => 'foo3@example.com',
+					'CATEGORIES' => 'groups,asecondgroup',
 				],
 				[
 					'ADR' => [
@@ -194,7 +248,8 @@ public function testSearchAttendee():void {
 					],
 					'LANG' => 'en_us',
 					'TZ' => 'Australia/Adelaide',
-					'PHOTO' => 'VALUE:BINARY:4242424242'
+					'PHOTO' => 'VALUE:BINARY:4242424242',
+					'CATEGORIES' => 'agroupthatswrong,asecondgroup',
 				],
 				[
 					'isLocalSystemBook' => true,
@@ -202,12 +257,141 @@ public function testSearchAttendee():void {
 					'ADR' => [
 						'ABC Street 2;01337 Village;;Germany',
 					],
+					'EMAIL' => 'foo4@example.com',
 					'LANG' => 'en_us',
 					'TZ' => 'Australia/Adelaide',
-					'PHOTO' => 'VALUE:BINARY:4242424242'
+					'PHOTO' => 'VALUE:BINARY:4242424242',
+					'CATEGORIES' => 'groupppppp',
 				],
 			]);
 
+		$groupmembers = $this->controller->getContactGroupMembers($groupname);
+		$this->assertCount(1, $groupmembers->getData());
+	}
+
+	public function testSearchAttendeeDisabled():void {
+		$this->manager->expects(self::once())
+			->method('isEnabled')
+			->willReturn(false);
+
+		$this->manager->expects(self::never())
+			->method('search');
+
+		$response = $this->controller->searchAttendee('search 123');
+
+		$this->assertInstanceOf(JSONResponse::class, $response);
+		$this->assertEquals([], $response->getData());
+		$this->assertEquals(200, $response->getStatus());
+	}
+
+	public function testSearchAttendee():void {
+		$user1 = [
+			'FN' => 'Person 1',
+			'ADR' => [
+				'33 42nd Street;Random Town;Some State;;United States',
+				';;5 Random Ave;12782 Some big city;Yet another state;United States',
+			],
+			'EMAIL' => [
+				'foo1@example.com',
+				'foo2@example.com',
+			],
+			'LANG' => [
+				'de',
+				'en'
+			],
+			'TZ' => [
+				'Europe/Berlin',
+				'UTC'
+			],
+			'PHOTO' => 'VALUE=uri:http://foo.bar'
+		];
+		$user2 = [
+			'FN' => 'Person 2',
+			'EMAIL' => 'foo3@example.com',
+		];
+		$user3 = [
+			'ADR' => [
+				'ABC Street 2;01337 Village;;Germany',
+			],
+			'LANG' => 'en_us',
+			'TZ' => 'Australia/Adelaide',
+			'PHOTO' => 'VALUE:BINARY:4242424242'
+		];
+		$user4 = [
+			'isLocalSystemBook' => true,
+			'FN' => 'Person 3',
+			'ADR' => [
+				'ABC Street 2;01337 Village;;Germany',
+			],
+			'LANG' => 'en_us',
+			'TZ' => 'Australia/Adelaide',
+			'PHOTO' => 'VALUE:BINARY:4242424242',
+			'CATEGORIES' => 'search 123'
+		];
+
+		$this->manager->expects(self::once())
+			->method('isEnabled')
+			->willReturn(true);
+		$this->service
+			->method('hasEmail')
+			->willReturnMap([
+				[$user1, true],
+				[$user2, true],
+				[$user3, false],
+				[$user4, true],
+			]);
+		$this->service
+			->method('isSystemBook')
+			->willReturnMap([
+				[$user1, false],
+				[$user2, false],
+				[$user3, false],
+				[$user4, true],
+			]);
+		$this->service
+			->method('getNameFromContact')
+			->willReturnMap([
+				[$user1, 'Person 1'],
+				[$user2, 'Person 2'],
+				[$user3, ''],
+			]);
+		$this->service->expects(self::exactly(2))
+			->method('getLanguageId')
+			->willReturnMap([
+				[$user1, 'de'],
+				[$user3, 'en_us'],
+			]);
+		$this->service->expects(self::exactly(2))
+			->method('getTimezoneId')
+			->willReturnMap([
+				[$user1, 'Europe/Berlin'],
+				[$user3, 'Australia/Adelaide'],
+			]);
+		$this->service->expects(self::exactly(2))
+			->method('getEmail')
+			->willReturnMap([
+				[$user1, [
+					'foo1@example.com',
+					'foo2@example.com',
+				]
+				],
+				[$user2, ['foo3@example.com']],
+				[$user3, ['foo5@example.com']],
+			]);
+		$this->service->method('getPhotoUri')
+			->willReturnMap([
+				[$user1, 'http://foo.bar'],
+				[$user2, null],
+				[$user3, null],
+				[$user4, null],
+			]);
+		$this->manager->expects(self::exactly(2))
+			->method('search')
+			->willReturnMap([
+				['search 123', ['FN', 'EMAIL'], [], [$user1, $user2, $user3, $user4]],
+				['search 123', ['CATEGORIES'], [], [$user4]]
+			]);
+
 		$response = $this->controller->searchAttendee('search 123');
 
 		$this->assertInstanceOf(JSONResponse::class, $response);
@@ -221,6 +405,7 @@ public function testSearchAttendee():void {
 				'lang' => 'de',
 				'tzid' => 'Europe/Berlin',
 				'photo' => 'http://foo.bar',
+				'type' => 'individual'
 			], [
 				'name' => 'Person 2',
 				'emails' => [
@@ -229,80 +414,102 @@ public function testSearchAttendee():void {
 				'lang' => null,
 				'tzid' => null,
 				'photo' => null,
+				'type' => 'individual'
 			]
 		], $response->getData());
 		$this->assertEquals(200, $response->getStatus());
 	}
 
 	public function testSearchPhotoDisabled():void {
-		$this->manager->expects($this->once())
+		$this->manager->expects(self::once())
 			->method('isEnabled')
-			->with()
 			->willReturn(false);
 
-		$this->manager->expects($this->never())
+		$this->manager->expects(self::never())
 			->method('search');
 
 		$response = $this->controller->searchAttendee('search 123');
 
-		$this->assertInstanceOf(JSONResponse::class, $response);
 		$this->assertEquals([], $response->getData());
 		$this->assertEquals(200, $response->getStatus());
 	}
 
 	public function testSearchPhoto():void {
+		$user1 = [
+			'FN' => 'Person 1',
+			'ADR' => [
+				'33 42nd Street;Random Town;Some State;;United States',
+				';;5 Random Ave;12782 Some big city;Yet another state;United States',
+			],
+			'EMAIL' => [
+				'foo1@example.com',
+				'foo2@example.com',
+			],
+			'LANG' => [
+				'de',
+				'en'
+			],
+			'TZ' => [
+				'Europe/Berlin',
+				'UTC'
+			],
+			'PHOTO' => 'VALUE=uri:http://foo123.bar'
+		];
+		$user2 = [
+			'FN' => 'Person 2',
+			'EMAIL' => 'foo3@example.com',
+			'PHOTO' => 'VALUE=uri:http://foo.bar'
+		];
+		$user3 = [
+			'ADR' => [
+				'ABC Street 2;01337 Village;;Germany',
+			],
+			'LANG' => 'en_us',
+			'TZ' => 'Australia/Adelaide',
+			'PHOTO' => 'VALUE:BINARY:4242424242'
+		];
+		$user4 = [
+			'isLocalSystemBook' => true,
+			'FN' => 'Person 3',
+			'ADR' => [
+				'ABC Street 2;01337 Village;;Germany',
+			],
+			'EMAIL' => 'foo5@example.com',
+			'LANG' => 'en_us',
+			'TZ' => 'Australia/Adelaide',
+			'PHOTO' => 'VALUE=uri:http://foo456.bar'
+		];
+
 		$this->manager->expects(self::once())
 			->method('isEnabled')
-			->with()
 			->willReturn(true);
-
+		$this->service->method('hasEmail')->willReturnMap([
+			[$user1, true],
+			[$user2, true],
+			[$user3, false],
+			[$user3, true],
+		]);
+		$this->service->method('isSystemBook');
+		$this->service->method('getEmail')
+			->willReturnMap([
+				[$user1, [
+					'foo1@example.com',
+					'foo2@example.com',
+				]
+				],
+				[$user2, ['foo3@example.com']],
+				[$user3, ['foo5@example.com']],
+			]);
+		$this->service->method('getNameFromContact')->willReturn('Person 2');
+		$this->service->method('getPhotoUri')->willReturn('http://foo.bar');
 		$this->manager->expects(self::once())
 			->method('search')
 			->with('foo3@example.com', ['EMAIL'])
 			->willReturn([
-				[
-					'FN' => 'Person 1',
-					'ADR' => [
-						'33 42nd Street;Random Town;Some State;;United States',
-						';;5 Random Ave;12782 Some big city;Yet another state;United States',
-					],
-					'EMAIL' => [
-						'foo1@example.com',
-						'foo2@example.com',
-					],
-					'LANG' => [
-						'de',
-						'en'
-					],
-					'TZ' => [
-						'Europe/Berlin',
-						'UTC'
-					],
-					'PHOTO' => 'VALUE=uri:http://foo123.bar'
-				],
-				[
-					'FN' => 'Person 2',
-					'EMAIL' => 'foo3@example.com',
-					'PHOTO' => 'VALUE=uri:http://foo.bar'
-				],
-				[
-					'ADR' => [
-						'ABC Street 2;01337 Village;;Germany',
-					],
-					'LANG' => 'en_us',
-					'TZ' => 'Australia/Adelaide',
-					'PHOTO' => 'VALUE:BINARY:4242424242'
-				],
-				[
-					'isLocalSystemBook' => true,
-					'FN' => 'Person 3',
-					'ADR' => [
-						'ABC Street 2;01337 Village;;Germany',
-					],
-					'LANG' => 'en_us',
-					'TZ' => 'Australia/Adelaide',
-					'PHOTO' => 'VALUE=uri:http://foo456.bar'
-				],
+				$user1,
+				$user2,
+				$user3,
+				$user4,
 			]);
 
 		$response = $this->controller->searchPhoto('foo3@example.com');
diff --git a/tests/php/unit/Service/ContactsServiceTest.php b/tests/php/unit/Service/ContactsServiceTest.php
new file mode 100644
index 000000000..986573f92
--- /dev/null
+++ b/tests/php/unit/Service/ContactsServiceTest.php
@@ -0,0 +1,96 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2014 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+namespace OCA\Calendar\Service;
+
+use ChristophWurst\Nextcloud\Testing\TestCase;
+
+class ContactsServiceTest extends TestCase {
+	private ContactsService $service;
+
+	public function setUp(): void {
+		$this->service = new ContactsService();
+	}
+
+	public function testGetEmail(): void {
+		$contact = ['EMAIL' => 'test@test.com'];
+		$this->assertEquals(['test@test.com'], $this->service->getEmail($contact));
+	}
+
+	public function testIsSystemBook(): void {
+		$contact = ['isLocalSystemBook' => true];
+		$this->assertTrue($this->service->isSystemBook($contact));
+	}
+
+	public function testIsNotSystemBook(): void {
+		$contact = ['isLocalSystemBook' => false];
+		$this->assertFalse($this->service->isSystemBook($contact));
+	}
+
+	public function testNotSetSystemBook(): void {
+		$this->assertFalse($this->service->isSystemBook([]));
+	}
+
+	public function testHasEmail(): void {
+		$contact = ['EMAIL' => 'test@test.com'];
+		$this->assertTrue($this->service->hasEmail($contact));
+	}
+
+	public function testHasNoEmail(): void {
+		$this->assertFalse($this->service->hasEmail([]));
+	}
+
+	public function testGetPhotoUri(): void {
+		$contact = ['PHOTO' => 'VALUE=uri:http://test'];
+		$this->assertEquals('http://test', $this->service->getPhotoUri($contact));
+	}
+
+	public function testGetPhotoInvalidUri(): void {
+		$contact = ['PHOTO' => 'VALUE=uri:thisisnotit'];
+		$this->assertNull($this->service->getPhotoUri($contact));
+	}
+
+	public function testGetPhotoUriNoPhoto(): void {
+		$this->assertNull($this->service->getPhotoUri([]));
+	}
+
+	public function testFilterGroupsWithCount(): void {
+		$contact = [
+			['CATEGORIES' => 'The Proclaimers,I\'m gonna be,When I go out,I would walk 500 Miles,I would walk 500 more'],
+			['CATEGORIES' => 'The Proclaimers,When I\'m lonely,I would walk 500 Miles,I would walk 500 more'],
+		];
+
+		$searchterm = 'walk';
+
+		$expected = [
+			'I would walk 500 Miles' => 2,
+			'I would walk 500 more' => 2,
+		];
+
+		$this->assertEqualsCanonicalizing($expected, $this->service->filterGroupsWithCount($contact, $searchterm));
+	}
+
+	public function testGetTimezoneId(): void {
+		$contact = ['TZ' => ['UTC']];
+		$this->assertEquals('UTC', $this->service->getTimezoneId($contact));
+	}
+
+	public function testGetLanguageId(): void {
+		$contact = ['LANG' => ['de_de']];
+		$this->assertEquals('de_de', $this->service->getLanguageId($contact));
+	}
+
+	public function testGetNameFromContact(): void {
+		$contact = ['FN' => 'test'];
+		$this->assertEquals('test', $this->service->getNameFromContact($contact));
+	}
+	
+	public function testGetNameFromContactNoName(): void {
+		$this->assertEquals('', $this->service->getNameFromContact([]));
+	}
+}