diff --git a/src/BaseEntity.php b/src/BaseDataTransferObject.php
similarity index 83%
rename from src/BaseEntity.php
rename to src/BaseDataTransferObject.php
index 1ea3f8a16b..5736cdf323 100644
--- a/src/BaseEntity.php
+++ b/src/BaseDataTransferObject.php
@@ -22,20 +22,20 @@
 namespace Friendica;
 
 /**
- * The API entity classes are meant as data transfer objects. As such, their member should be protected.
+ * These data transfer object classes are meant for API representations. As such, their members should be protected.
  * Then the JsonSerializable interface ensures the protected members will be included in a JSON encode situation.
  *
  * Constructors are supposed to take as arguments the Friendica dependencies/model/collection/data it needs to
  * populate the class members.
  */
-abstract class BaseEntity implements \JsonSerializable
+abstract class BaseDataTransferObject implements \JsonSerializable
 {
 	/**
 	 * Returns the current entity as an json array
 	 *
 	 * @return array
 	 */
-	public function jsonSerialize()
+	public function jsonSerialize(): array
 	{
 		return $this->toArray();
 	}
@@ -45,7 +45,7 @@ abstract class BaseEntity implements \JsonSerializable
 	 *
 	 * @return array
 	 */
-	public function toArray()
+	public function toArray(): array
 	{
 		return get_object_vars($this);
 	}
diff --git a/src/BaseModel.php b/src/BaseModel.php
index 41320d8bd5..a2750d568d 100644
--- a/src/BaseModel.php
+++ b/src/BaseModel.php
@@ -31,7 +31,7 @@ use Psr\Log\LoggerInterface;
  *
  * @property int id
  */
-abstract class BaseModel extends BaseEntity
+abstract class BaseModel extends BaseDataTransferObject
 {
 	/** @var Database */
 	protected $dba;
@@ -67,7 +67,7 @@ abstract class BaseModel extends BaseEntity
 		$this->originalData = $data;
 	}
 
-	public function getOriginalData()
+	public function getOriginalData(): array
 	{
 		return $this->originalData;
 	}
@@ -84,7 +84,7 @@ abstract class BaseModel extends BaseEntity
 	 * @param array     $data
 	 * @return BaseModel
 	 */
-	public static function createFromPrototype(BaseModel $prototype, array $data)
+	public static function createFromPrototype(BaseModel $prototype, array $data): BaseModel
 	{
 		$model = clone $prototype;
 		$model->data = $data;
@@ -100,7 +100,7 @@ abstract class BaseModel extends BaseEntity
 	 * @param $name
 	 * @return bool
 	 */
-	public function __isset($name)
+	public function __isset($name): bool
 	{
 		return in_array($name, array_merge(array_keys($this->data), array_keys(get_object_vars($this))));
 	}
@@ -126,15 +126,19 @@ abstract class BaseModel extends BaseEntity
 	}
 
 	/**
+	 * * Magic setter. This allows to set model fields with the following syntax:
+	 * - $model->field = $value (outside of class)
+	 * - $this->field = $value (inside of class)
+	 *
 	 * @param string $name
-	 * @param mixed $value
+	 * @param mixed  $value
 	 */
-	public function __set($name, $value)
+	public function __set(string $name, $value)
 	{
 		$this->data[$name] = $value;
 	}
 
-	public function toArray()
+	public function toArray(): array
 	{
 		return $this->data;
 	}
diff --git a/src/Object/Api/Friendica/Notification.php b/src/Object/Api/Friendica/Notification.php
index aee787da17..60c824a566 100644
--- a/src/Object/Api/Friendica/Notification.php
+++ b/src/Object/Api/Friendica/Notification.php
@@ -21,7 +21,7 @@
 
 namespace Friendica\Object\Api\Friendica;
 
-use Friendica\BaseEntity;
+use Friendica\BaseDataTransferObject;
 use Friendica\Content\Text\BBCode;
 use Friendica\Content\Text\HTML;
 use Friendica\Model\Notify;
@@ -33,7 +33,7 @@ use Friendica\Util\Temporal;
  *
  * @see https://github.com/friendica/friendica/blob/develop/doc/API-Entities.md#notification
  */
-class Notification extends BaseEntity
+class Notification extends BaseDataTransferObject
 {
 	/** @var integer */
 	protected $id;
diff --git a/src/Object/Api/Mastodon/Account.php b/src/Object/Api/Mastodon/Account.php
index 587c6ce6d4..e74339563f 100644
--- a/src/Object/Api/Mastodon/Account.php
+++ b/src/Object/Api/Mastodon/Account.php
@@ -22,7 +22,7 @@
 namespace Friendica\Object\Api\Mastodon;
 
 use Friendica\App\BaseURL;
-use Friendica\BaseEntity;
+use Friendica\BaseDataTransferObject;
 use Friendica\Collection\Api\Mastodon\Fields;
 use Friendica\Content\Text\BBCode;
 use Friendica\Database\DBA;
@@ -34,7 +34,7 @@ use Friendica\Util\DateTimeFormat;
  *
  * @see https://docs.joinmastodon.org/entities/account
  */
-class Account extends BaseEntity
+class Account extends BaseDataTransferObject
 {
 	/** @var string */
 	protected $id;
@@ -138,7 +138,7 @@ class Account extends BaseEntity
 	 *
 	 * @return array
 	 */
-	public function toArray()
+	public function toArray(): array
 	{
 		$account = parent::toArray();
 
diff --git a/src/Object/Api/Mastodon/Activity.php b/src/Object/Api/Mastodon/Activity.php
index a73307eb47..73bde98a43 100644
--- a/src/Object/Api/Mastodon/Activity.php
+++ b/src/Object/Api/Mastodon/Activity.php
@@ -21,14 +21,14 @@
 
 namespace Friendica\Object\Api\Mastodon;
 
-use Friendica\BaseEntity;
+use Friendica\BaseDataTransferObject;
 
 /**
  * Class Activity
  *
  * @see https://docs.joinmastodon.org/entities/activity
  */
-class Activity extends BaseEntity
+class Activity extends BaseDataTransferObject
 {
 	/** @var string (UNIX Timestamp) */
 	protected $week;
diff --git a/src/Object/Api/Mastodon/Application.php b/src/Object/Api/Mastodon/Application.php
index d26d270d98..8cac4aaf79 100644
--- a/src/Object/Api/Mastodon/Application.php
+++ b/src/Object/Api/Mastodon/Application.php
@@ -21,14 +21,14 @@
 
 namespace Friendica\Object\Api\Mastodon;
 
-use Friendica\BaseEntity;
+use Friendica\BaseDataTransferObject;
 
 /**
  * Class Application
  *
  * @see https://docs.joinmastodon.org/entities/application
  */
-class Application extends BaseEntity
+class Application extends BaseDataTransferObject
 {
 	/** @var string */
 	protected $name;
diff --git a/src/Object/Api/Mastodon/Attachment.php b/src/Object/Api/Mastodon/Attachment.php
index 1651e9c40c..cc55b3715c 100644
--- a/src/Object/Api/Mastodon/Attachment.php
+++ b/src/Object/Api/Mastodon/Attachment.php
@@ -21,14 +21,14 @@
 
 namespace Friendica\Object\Api\Mastodon;
 
-use Friendica\BaseEntity;
+use Friendica\BaseDataTransferObject;
 
 /**
  * Class Attachment
  *
  * @see https://docs.joinmastodon.org/entities/attachment
  */
-class Attachment extends BaseEntity
+class Attachment extends BaseDataTransferObject
 {
 	/** @var string */
 	protected $id;
@@ -67,7 +67,7 @@ class Attachment extends BaseEntity
 	 *
 	 * @return array
 	 */
-	public function toArray()
+	public function toArray(): array
 	{
 		$attachment = parent::toArray();
 
diff --git a/src/Object/Api/Mastodon/Card.php b/src/Object/Api/Mastodon/Card.php
index 2f46e4779d..33e3c10599 100644
--- a/src/Object/Api/Mastodon/Card.php
+++ b/src/Object/Api/Mastodon/Card.php
@@ -21,14 +21,14 @@
 
 namespace Friendica\Object\Api\Mastodon;
 
-use Friendica\BaseEntity;
+use Friendica\BaseDataTransferObject;
 
 /**
  * Class Card
  *
  * @see https://docs.joinmastodon.org/entities/card
  */
-class Card extends BaseEntity
+class Card extends BaseDataTransferObject
 {
 	/** @var string */
 	protected $url;
@@ -67,10 +67,10 @@ class Card extends BaseEntity
 	 *
 	 * @return array
 	 */
-	public function toArray()
+	public function toArray(): array
 	{
 		if (empty($this->url)) {
-			return null;
+			return [];
 		}
 
 		return parent::toArray();
diff --git a/src/Object/Api/Mastodon/Emoji.php b/src/Object/Api/Mastodon/Emoji.php
index 1f6f121507..837b186b60 100644
--- a/src/Object/Api/Mastodon/Emoji.php
+++ b/src/Object/Api/Mastodon/Emoji.php
@@ -21,14 +21,14 @@
 
 namespace Friendica\Object\Api\Mastodon;
 
-use Friendica\BaseEntity;
+use Friendica\BaseDataTransferObject;
 
 /**
  * Class Emoji
  *
  * @see https://docs.joinmastodon.org/entities/emoji/
  */
-class Emoji extends BaseEntity
+class Emoji extends BaseDataTransferObject
 {
 	//Required attributes
 	/** @var string */
diff --git a/src/Object/Api/Mastodon/Error.php b/src/Object/Api/Mastodon/Error.php
index 0bfd1826c6..44573987f2 100644
--- a/src/Object/Api/Mastodon/Error.php
+++ b/src/Object/Api/Mastodon/Error.php
@@ -21,14 +21,14 @@
 
 namespace Friendica\Object\Api\Mastodon;
 
-use Friendica\BaseEntity;
+use Friendica\BaseDataTransferObject;
 
 /**
  * Class Error
  *
  * @see https://docs.joinmastodon.org/entities/error
  */
-class Error extends BaseEntity
+class Error extends BaseDataTransferObject
 {
 	/** @var string */
 	protected $error;
@@ -53,7 +53,7 @@ class Error extends BaseEntity
 	 *
 	 * @return array
 	 */
-	public function toArray()
+	public function toArray(): array
 	{
 		$error = parent::toArray();
 
diff --git a/src/Object/Api/Mastodon/Field.php b/src/Object/Api/Mastodon/Field.php
index 95cbc89dfa..91e8fb1911 100644
--- a/src/Object/Api/Mastodon/Field.php
+++ b/src/Object/Api/Mastodon/Field.php
@@ -21,14 +21,14 @@
 
 namespace Friendica\Object\Api\Mastodon;
 
-use Friendica\BaseEntity;
+use Friendica\BaseDataTransferObject;
 
 /**
  * Class Field
  *
  * @see https://docs.joinmastodon.org/entities/field/
  */
-class Field extends BaseEntity
+class Field extends BaseDataTransferObject
 {
 	/** @var string */
 	protected $name;
diff --git a/src/Object/Api/Mastodon/Instance.php b/src/Object/Api/Mastodon/Instance.php
index 6105a8bee1..d08637509d 100644
--- a/src/Object/Api/Mastodon/Instance.php
+++ b/src/Object/Api/Mastodon/Instance.php
@@ -21,7 +21,7 @@
 
 namespace Friendica\Object\Api\Mastodon;
 
-use Friendica\BaseEntity;
+use Friendica\BaseDataTransferObject;
 use Friendica\Database\DBA;
 use Friendica\DI;
 use Friendica\Model\User;
@@ -32,7 +32,7 @@ use Friendica\Module\Register;
  *
  * @see https://docs.joinmastodon.org/api/entities/#instance
  */
-class Instance extends BaseEntity
+class Instance extends BaseDataTransferObject
 {
 	/** @var string (URL) */
 	protected $uri;
diff --git a/src/Object/Api/Mastodon/Mention.php b/src/Object/Api/Mastodon/Mention.php
index 22e623e604..6de6f00487 100644
--- a/src/Object/Api/Mastodon/Mention.php
+++ b/src/Object/Api/Mastodon/Mention.php
@@ -22,14 +22,14 @@
 namespace Friendica\Object\Api\Mastodon;
 
 use Friendica\App\BaseURL;
-use Friendica\BaseEntity;
+use Friendica\BaseDataTransferObject;
 
 /**
  * Class Mention
  *
  * @see https://docs.joinmastodon.org/entities/mention
  */
-class Mention extends BaseEntity
+class Mention extends BaseDataTransferObject
 {
 	/** @var string */
 	protected $id;
diff --git a/src/Object/Api/Mastodon/Relationship.php b/src/Object/Api/Mastodon/Relationship.php
index bb3aa55416..06f973788c 100644
--- a/src/Object/Api/Mastodon/Relationship.php
+++ b/src/Object/Api/Mastodon/Relationship.php
@@ -21,7 +21,7 @@
 
 namespace Friendica\Object\Api\Mastodon;
 
-use Friendica\BaseEntity;
+use Friendica\BaseDataTransferObject;
 use Friendica\Model\Contact;
 use Friendica\Util\Network;
 
@@ -30,7 +30,7 @@ use Friendica\Util\Network;
  *
  * @see https://docs.joinmastodon.org/api/entities/#relationship
  */
-class Relationship extends BaseEntity
+class Relationship extends BaseDataTransferObject
 {
 	/** @var int */
 	protected $id;
diff --git a/src/Object/Api/Mastodon/Stats.php b/src/Object/Api/Mastodon/Stats.php
index 6ead526729..398b7252d9 100644
--- a/src/Object/Api/Mastodon/Stats.php
+++ b/src/Object/Api/Mastodon/Stats.php
@@ -21,7 +21,7 @@
 
 namespace Friendica\Object\Api\Mastodon;
 
-use Friendica\BaseEntity;
+use Friendica\BaseDataTransferObject;
 use Friendica\Core\Protocol;
 use Friendica\Database\DBA;
 use Friendica\DI;
@@ -31,7 +31,7 @@ use Friendica\DI;
  *
  * @see https://docs.joinmastodon.org/api/entities/#stats
  */
-class Stats extends BaseEntity
+class Stats extends BaseDataTransferObject
 {
 	/** @var int */
 	protected $user_count = 0;
diff --git a/src/Object/Api/Mastodon/Status.php b/src/Object/Api/Mastodon/Status.php
index d14eb4efa3..c4b7e397dc 100644
--- a/src/Object/Api/Mastodon/Status.php
+++ b/src/Object/Api/Mastodon/Status.php
@@ -21,7 +21,7 @@
 
 namespace Friendica\Object\Api\Mastodon;
 
-use Friendica\BaseEntity;
+use Friendica\BaseDataTransferObject;
 use Friendica\Content\Text\BBCode;
 use Friendica\Object\Api\Mastodon\Status\Counts;
 use Friendica\Object\Api\Mastodon\Status\UserAttributes;
@@ -32,7 +32,7 @@ use Friendica\Util\DateTimeFormat;
  *
  * @see https://docs.joinmastodon.org/entities/status
  */
-class Status extends BaseEntity
+class Status extends BaseDataTransferObject
 {
 	/** @var string */
 	protected $id;
@@ -143,7 +143,7 @@ class Status extends BaseEntity
 	 *
 	 * @return array
 	 */
-	public function toArray()
+	public function toArray(): array
 	{
 		$status = parent::toArray();
 
diff --git a/src/Object/Api/Mastodon/Tag.php b/src/Object/Api/Mastodon/Tag.php
index 1e74eae00f..c83c3bcf35 100644
--- a/src/Object/Api/Mastodon/Tag.php
+++ b/src/Object/Api/Mastodon/Tag.php
@@ -22,14 +22,14 @@
 namespace Friendica\Object\Api\Mastodon;
 
 use Friendica\App\BaseURL;
-use Friendica\BaseEntity;
+use Friendica\BaseDataTransferObject;
 
 /**
  * Class Tag
  *
  * @see https://docs.joinmastodon.org/entities/tag
  */
-class Tag extends BaseEntity
+class Tag extends BaseDataTransferObject
 {
 	/** @var string */
 	protected $name;
diff --git a/src/Object/Api/Twitter/User.php b/src/Object/Api/Twitter/User.php
index 1cdd699de8..7793fbc26f 100644
--- a/src/Object/Api/Twitter/User.php
+++ b/src/Object/Api/Twitter/User.php
@@ -21,14 +21,14 @@
 
 namespace Friendica\Object\Api\Twitter;
 
-use Friendica\BaseEntity;
+use Friendica\BaseDataTransferObject;
 use Friendica\Content\ContactSelector;
 use Friendica\Content\Text\BBCode;
 
 /**
  * @see https://developer.twitter.com/en/docs/tweets/data-dictionary/overview/user-object
  */
-class User extends BaseEntity
+class User extends BaseDataTransferObject
 {
 	/** @var int */
 	protected $id;