diff --git a/lib/Controller/PersonalSettingsController.php b/lib/Controller/PersonalSettingsController.php
index 4d7d417..3e1cb05 100644
--- a/lib/Controller/PersonalSettingsController.php
+++ b/lib/Controller/PersonalSettingsController.php
@@ -35,12 +35,8 @@ class PersonalSettingsController extends Controller {
 	 */
 	public function metrics(): JSONResponse {
 		$metrics = $this->metricsReader->metrics($this->userId);
-
-		$metricsArrays = array_map(function (PodcastMetrics $metric) {
-			return $metric->toArray();
-		}, $metrics);
 		return new JSONResponse([
-			'subscriptions' => $metricsArrays,
+			'subscriptions' => $metrics,
 		]);
 	}
 }
diff --git a/lib/Core/PodcastData/PodcastData.php b/lib/Core/PodcastData/PodcastData.php
index 8b7ee10..e23b40f 100644
--- a/lib/Core/PodcastData/PodcastData.php
+++ b/lib/Core/PodcastData/PodcastData.php
@@ -4,9 +4,10 @@ declare(strict_types=1);
 namespace OCA\GPodderSync\Core\PodcastData;
 
 use DateTime;
+use JsonSerializable;
 use SimpleXMLElement;
 
-class PodcastData {
+class PodcastData implements JsonSerializable {
 	private string $title;
 	private string $author;
 	private string $link;
@@ -30,6 +31,10 @@ class PodcastData {
 		$this->fetchedAtUnix = $fetchedAtUnix;
 	}
 
+	/**
+	 * @return PodcastData
+	 * @throws Exception if the XML data could not be parsed.
+	 */
 	public static function parseRssXml(string $xmlString, ?int $fetchedAtUnix = null): PodcastData {
 		$xml = new SimpleXMLElement($xmlString);
 		$channel = $xml->channel;
@@ -45,7 +50,7 @@ class PodcastData {
 		);
 	}
 
-	private static function getXPathContent(SimpleXMLElement $xml, string $xpath) {
+	private static function getXPathContent(SimpleXMLElement $xml, string $xpath): ?string {
 		$match = $xml->xpath($xpath);
 		if ($match) {
 			return (string)$match[0];
@@ -53,7 +58,7 @@ class PodcastData {
 		return null;
 	}
 
-	private static function getXPathAttribute(SimpleXMLElement $xml, string $xpath) {
+	private static function getXPathAttribute(SimpleXMLElement $xml, string $xpath): ?string {
 		$match = $xml->xpath($xpath);
 		if ($match) {
 			return (string)$match[0][0];
@@ -111,7 +116,7 @@ class PodcastData {
 	}
 
 	/**
-	 * @return array
+	 * @return array<string,mixed>
 	 */
 	public function toArray(): array {
 		return
@@ -125,6 +130,13 @@ class PodcastData {
 		];
 	}
 
+	/**
+	 * @return array<string,mixed>
+	 */
+	public function jsonSerialize(): mixed {
+		return $this->toArray();
+	}
+
 	/**
 	 * @return PodcastData
 	 */
diff --git a/lib/Core/PodcastData/PodcastMetrics.php b/lib/Core/PodcastData/PodcastMetrics.php
index aa76262..927cade 100644
--- a/lib/Core/PodcastData/PodcastMetrics.php
+++ b/lib/Core/PodcastData/PodcastMetrics.php
@@ -3,7 +3,9 @@ declare(strict_types=1);
 
 namespace OCA\GPodderSync\Core\PodcastData;
 
-class PodcastMetrics {
+use JsonSerializable;
+
+class PodcastMetrics implements JsonSerializable {
 	private string $url;
 	private int $listenedSeconds;
 	private PodcastActionCounts $actionCounts;
@@ -56,6 +58,9 @@ class PodcastMetrics {
 		return $this->podcastData;
 	}
 
+	/**
+	 * @return array<string,mixed>
+	 */
 	public function toArray(): array {
 		return
 		[
@@ -65,4 +70,11 @@ class PodcastMetrics {
 			'podcastData' => $this->podcastData->toArray(),
 		];
 	}
+
+	/**
+	 * @return array<string,mixed>
+	 */
+	public function jsonSerialize(): mixed {
+		return $this->toArray();
+	}
 }