diff --git a/services/trackers/AggregateTracker.js b/services/trackers/AggregateTracker.js
index 41afe97..ef479f1 100644
--- a/services/trackers/AggregateTracker.js
+++ b/services/trackers/AggregateTracker.js
@@ -1,13 +1,17 @@
 class AggregateTracker {
+  #trackers = []
+
   constructor(trackers) {
-    this._trackers = trackers;
+    this.#trackers = trackers;
   }
 
-  poll() {
-    const media = []
-    for (let tracker of this._trackers)
-      media.push.apply(tracker.poll());
+  async poll() {
+    let media = []
+    for (let tracker of this.#trackers)
+      media = media.concat(await tracker.poll());
 
     return media;
   }
-}
\ No newline at end of file
+}
+
+module.exports = AggregateTracker;
\ No newline at end of file
diff --git a/services/trackers/PlexTracker.js b/services/trackers/PlexTracker.js
index 9a41155..2041acf 100644
--- a/services/trackers/PlexTracker.js
+++ b/services/trackers/PlexTracker.js
@@ -2,39 +2,41 @@ const axios = require("axios");
 const Song = require("../../models/song");
 
 class PlexTracker {
+  #config = null;
+  #cache = [];
+
   constructor(config) {
-    this._config = config;
-    this._cache = []
+    this.#config = config;
   }
 
   async poll(useCache = false) {
-    if (!this._config.token || !this._config.url)
+    if (!this.#config.token || !this.#config.url)
       return [];
     if (useCache)
-      return cache;
+      return this.#cache;
 
-    const response = await axios.get(this._config.url + "/status/sessions", {
+    const response = await axios.get(this.#config.url + "/status/sessions", {
       headers: {
         "Accept": "application/json",
-        "X-Plex-Token": this._config.token
+        "X-Plex-Token": this.#config.token
       }
     });
 
     if (!response.data.MediaContainer?.Metadata) {
-      cache = [];
-      return cache;
+      this.#cache = [];
+      return this.#cache;
     }
 
     const filtered = response.data.MediaContainer?.Metadata.filter(m => this.#filter(m));
-    cache = filtered.map(this.#transform);
-    return cache;
+    this.#cache = filtered.map(m => this.#transform(m));
+    return this.#cache;
   }
 
   #filter(data) {
-    if (!this._config.filters || this._config.filters.length == 0)
+    if (!this.#config.filters || this.#config.filters.length == 0)
       return true;
 
-    for (let filter of this._config.filters) {
+    for (let filter of this.#config.filters) {
       if (filter.library && !filter.library.some(l => l == data.librarySectionTitle))
         continue;
       if (filter.ip && !filter.ip.some(l => l == data.address))
diff --git a/services/trackers/SpotifyTracker.js b/services/trackers/SpotifyTracker.js
index 5fc38aa..db52a6e 100644
--- a/services/trackers/SpotifyTracker.js
+++ b/services/trackers/SpotifyTracker.js
@@ -1,47 +1,63 @@
 const axios = require("axios");
-const logger = require("./logging");
+const logger = require("../logging");
 const fs = require("fs/promises");
+const fss = require("fs");
 const Song = require("../../models/song");
 
 class SpotifyTracker {
-  constructor(config, token) {
-    this._token = token;
-    this._cache = null;
-    this._config = config;
-    this._auth = new Buffer.from(config.client_id + ':' + config.client_secret).toString('base64');
+  #config = null;
+  #token = null;
+  #cache = null;
+  #auth = null;
+
+  constructor(config, token = null) {
+    this.#config = config;
+    this.#token = token;
+    this.#cache = null;
+    this.#auth = new Buffer.from(config.client_id + ':' + config.client_secret).toString('base64');
   }
 
   async poll(useCache = false) {
-    if (token == null)
-      return null;
+    if (this.#token == null)
+      return [];
     if (useCache)
-      return cache;
+      return this.#cache;
 
-    if (token.expires_at < Date.now() + 300)
+    if (this.#token.expires_at < Date.now() + 300)
       await this.#refreshTokenIfNeeded();
 
     try {
       const response = await axios.get("https://api.spotify.com/v1/me/player/currently-playing",
         {
           headers: {
-            "Authorization": "Bearer " + token["access_token"]
+            "Authorization": "Bearer " + this.#token.access_token
           }
         }
       );
 
       if (!response.data) {
-        cache = null;
-        return null;
+        this.#cache = [];
+        return this.#cache;
       }
 
-      cache = [this.#transform(response.data)];
-      return cache;
+      this.#cache = [this.#transform(response.data)];
+      return this.#cache;
     } catch (ex) {
       logger.error(ex, "Failed to get currently playing data from Spotify.");
       return [];
     }
   }
 
+  async loadCredentials() {
+    if (!fss.existsSync("credentials.spotify.json")) {
+      logger.info("No Spotify credentials found.");
+      return;
+    }
+  
+    const content = await fs.readFile("credentials.spotify.json", "utf-8");
+    this.#token = JSON.parse(content);
+  }
+
   #transform(data) {
     const item = data.item;
     const artists = item.artists.map(a => a.name);
@@ -51,18 +67,18 @@ class SpotifyTracker {
   }
 
   async #refreshTokenIfNeeded() {
-    if (!this._token || this._token.expires_at && this._token.expires_at - Date.now() > 900)
+    if (!this.#token || this.#token.expires_at && this.#token.expires_at - Date.now() > 900)
       return false;
 
     const response = await axios.post("https://accounts.spotify.com/api/token",
       {
-        client_id: this._config.client_id,
-        refresh_token: this._token.refresh_token,
+        client_id: this.#config.client_id,
+        refresh_token: this.#token.refresh_token,
         grant_type: "refresh_token"
       },
       {
         headers: {
-          "Authorization": "Basic " + this._auth,
+          "Authorization": "Basic " + this.#auth,
           "Content-Type": "application/x-www-form-urlencoded"
         }
       }
@@ -71,9 +87,9 @@ class SpotifyTracker {
     const data = response.data;
     data["expires_at"] = Date.now() + data["expires_in"] * 1000;
     if (!data["refresh_token"])
-      data["refresh_token"] = this._token.refresh_token;
+      data["refresh_token"] = this.#token.refresh_token;
 
-    this._token = data;
+    this.#token = data;
     await fs.writeFile("credentials.spotify.json", JSON.stringify(data));
     logger.debug("Updated access token for Spotify.");
     return true;