diff --git a/karma.conf.js b/karma.conf.js
index 681afdd..de9e608 100644
--- a/karma.conf.js
+++ b/karma.conf.js
@@ -9,14 +9,7 @@ module.exports = config => {
     files: [
       './bin/test.min.js',
       {
-        pattern: 'test-assets/json/*.json',
-        watched: false,
-        included: false,
-        served: true,
-        nocache: false
-      },
-      {
-        pattern: 'test-assets/l10n/de-DE/*.json',
+        pattern: 'test-assets/**/*.*',
         watched: false,
         included: false,
         served: true,
diff --git a/src/l10n/resource_manager.js b/src/l10n/resource_manager.js
new file mode 100644
index 0000000..44b8dee
--- /dev/null
+++ b/src/l10n/resource_manager.js
@@ -0,0 +1,178 @@
+goog.module('clulib.l10n.ResourceManager');
+
+const ResourceBundle = goog.require('clulib.l10n.ResourceBundle');
+
+/**
+ * Manages multiple ResourceBundles for multiple locales.
+ *
+ * Loads json localization files via pattern `baseUrl/locale/id.json`.
+ */
+class ResourceManager {
+  /**
+   * @param {Array<string>} bundleIds
+   * @param {Array<string>} locales
+   * @param {string} baseUrl
+   */
+  constructor (bundleIds, locales, baseUrl) {
+    /**
+     * @type {Array<string>}
+     * @private
+     */
+    this.bundleIds_ = bundleIds;
+
+    /**
+     * @type {Array<string>}
+     * @private
+     */
+    this.locales_ = locales;
+
+    /**
+     * @type {string}
+     * @private
+     */
+    this.baseUrl_ = baseUrl;
+
+    /**
+     * @type {?string}
+     * @private
+     */
+    this.currentLocale_ = null;
+
+    /**
+     * @type {Map<string, Map<string, ResourceBundle>>}
+     * @private
+     */
+    this.bundles_ = new Map();
+
+    locales.forEach(locale => {
+      const localeMap = new Map();
+
+      bundleIds.forEach(bundleId => {
+        localeMap.set(bundleId, new ResourceBundle(bundleId, locale, baseUrl));
+      });
+
+      this.bundles_.set(locale, localeMap);
+    });
+  }
+
+  /**
+   * @returns {?string}
+   */
+  get currentLocale () {
+    return this.currentLocale_;
+  }
+
+  /**
+   * Checks if the locale is valid for this ResourceManager
+   *
+   * @param {string} locale
+   * @returns {boolean}
+   */
+  isLocaleValid (locale) {
+    return this.locales_.includes(locale);
+  }
+
+  // eslint-disable-next-line valid-jsdoc
+  /**
+   * Changes the current locale, loads the resource files if necessary.
+   *
+   * @param {string} locale
+   * @returns {Promise<void>}
+   */
+  async changeLocale (locale) {
+    if (!this.isLocaleValid(locale))
+      throw new Error(`Locale '${locale}' is not registered with this ResourceManager.`);
+
+    const bundleLoaders = Array.from(this.bundles_.get(locale).values())
+      .map(bundle => bundle.load());
+
+    await Promise.all(bundleLoaders);
+
+    this.currentLocale_ = locale;
+  }
+
+  /**
+   * Gets a specific bundle for the current locale.
+   *
+   * @param {string} bundleId
+   * @returns {ResourceBundle}
+   */
+  getBundle (bundleId) {
+    if (this.currentLocale_ == null)
+      throw new Error('No locale set!');
+
+    return this.bundles_.get(/** @type {!string} */ (this.currentLocale_)).get(bundleId);
+  }
+
+  /**
+   * Checks if a bundle contains a localization key.
+   *
+   * @param {string} bundleId
+   * @param {string} key
+   * @returns {boolean}
+   */
+  contains (bundleId, key) {
+    return this.getBundle(bundleId).contains(key);
+  }
+
+  /**
+   * Gets an object from the json localization file of the current bundle.
+   *
+   * @param {string} bundleId
+   * @param {string} key
+   * @returns {Object}
+   */
+  getObject (bundleId, key) {
+    return this.getBundle(bundleId).getObject(key);
+  }
+
+  /**
+   * Gets an array from the json localization file of the current bundle.
+   *
+   * @param {string} bundleId
+   * @param {string} key
+   * @returns {Array}
+   */
+  getArray (bundleId, key) {
+    return this.getBundle(bundleId).getArray(key);
+  }
+
+  /**
+   * Gets a boolean from the json localization file of the current bundle.
+   *
+   * @param {string} bundleId
+   * @param {string} key
+   * @returns {boolean}
+   */
+  getBoolean (bundleId, key) {
+    return this.getBundle(bundleId).getBoolean(key);
+  }
+
+  /**
+   * Gets a number from the json localization file of the current bundle.
+   *
+   * @param {string} bundleId
+   * @param {string} key
+   * @returns {number}
+   */
+  getNumber (bundleId, key) {
+    return this.getBundle(bundleId).getNumber(key);
+  }
+
+  /**
+   * Gets a string from the json localization file of the current bundle.
+   *
+   * Takes an optional `replaceObject` which will replace placeholder keys in the string.
+   * An object with key `foo` will replace all placeholders `{foo}`.
+   *
+   * @param {string} bundleId
+   * @param {string} key
+   * @param {Object=} replaceObject
+   * @returns {string}
+   */
+  getString (bundleId, key, replaceObject = null) {
+    return this.getBundle(bundleId).getString(key, replaceObject);
+  }
+}
+
+exports = ResourceManager;
diff --git a/test-assets/l10n/de-DE/test.json b/test-assets/l10n/de-DE/test.json
index 34af819..e37d2b5 100644
--- a/test-assets/l10n/de-DE/test.json
+++ b/test-assets/l10n/de-DE/test.json
@@ -1,16 +1,16 @@
 {
-  "string": "Hello, world!",
+  "string": "Hallo, Welt!",
   "array": [
     0,
     1,
     2
   ],
   "object": {
-    "one": 1,
-    "two": 2,
-    "three": 3
+    "eins": 1,
+    "zwei": 2,
+    "drei": 3
   },
   "number": 10,
   "boolean": false,
-  "string-placeholder": "Hello {to}, my name is {from}."
+  "string-placeholder": "Hallo {to}, mein name ist {from}."
 }
diff --git a/test-assets/l10n/en-GB/test.json b/test-assets/l10n/en-GB/test.json
new file mode 100644
index 0000000..34af819
--- /dev/null
+++ b/test-assets/l10n/en-GB/test.json
@@ -0,0 +1,16 @@
+{
+  "string": "Hello, world!",
+  "array": [
+    0,
+    1,
+    2
+  ],
+  "object": {
+    "one": 1,
+    "two": 2,
+    "three": 3
+  },
+  "number": 10,
+  "boolean": false,
+  "string-placeholder": "Hello {to}, my name is {from}."
+}
diff --git a/test/l10n/resource_bundle_spec.js b/test/l10n/resource_bundle_spec.js
index 801e976..be4d727 100644
--- a/test/l10n/resource_bundle_spec.js
+++ b/test/l10n/resource_bundle_spec.js
@@ -21,11 +21,11 @@ exports = function () {
       expect(bundle.getArray('array')).toEqual([0, 1, 2]);
       expect(bundle.getBoolean('boolean')).toBe(false);
       expect(bundle.getNumber('number')).toBe(10);
-      expect(bundle.getString('string')).toBe('Hello, world!');
-      expect(bundle.getObject('object')).toEqual({'one': 1, 'two': 2, 'three': 3});
+      expect(bundle.getString('string')).toBe('Hallo, Welt!');
+      expect(bundle.getObject('object')).toEqual({'eins': 1, 'zwei': 2, 'drei': 3});
 
       expect(bundle.getString('string-placeholder', {'from': 'Bob', 'to': 'Max'}))
-        .toBe('Hello Max, my name is Bob.');
+        .toBe('Hallo Max, mein name ist Bob.');
     });
   });
 };
diff --git a/test/l10n/resource_manager_spec.js b/test/l10n/resource_manager_spec.js
new file mode 100644
index 0000000..3e1aabb
--- /dev/null
+++ b/test/l10n/resource_manager_spec.js
@@ -0,0 +1,42 @@
+goog.module('test.clulib.l10n.ResourceManager');
+
+const ResourceManager = goog.require('clulib.l10n.ResourceManager');
+const env = goog.require('testing.environment');
+
+const base = `${env.basePath}/test-assets/l10n`;
+
+exports = function () {
+  describe('clulib.l10n.ResourceManager', () => {
+    it('should load resource files in different languages', async () => {
+      const manager = new ResourceManager(['test'], ['de-DE', 'en-GB'], base);
+
+      expect(manager.currentLocale).toBe(null);
+
+      await manager.changeLocale('de-DE');
+
+      expect(manager.contains('test', 'string-placeholder')).toBe(true);
+
+      expect(manager.getArray('test', 'array')).toEqual([0, 1, 2]);
+      expect(manager.getBoolean('test', 'boolean')).toBe(false);
+      expect(manager.getNumber('test', 'number')).toBe(10);
+      expect(manager.getString('test', 'string')).toBe('Hallo, Welt!');
+      expect(manager.getObject('test', 'object')).toEqual({'eins': 1, 'zwei': 2, 'drei': 3});
+
+      expect(manager.getString('test', 'string-placeholder', {'from': 'Bob', 'to': 'Max'}))
+        .toBe('Hallo Max, mein name ist Bob.');
+
+      await manager.changeLocale('en-GB');
+
+      expect(manager.contains('test', 'string-placeholder')).toBe(true);
+
+      expect(manager.getArray('test', 'array')).toEqual([0, 1, 2]);
+      expect(manager.getBoolean('test', 'boolean')).toBe(false);
+      expect(manager.getNumber('test', 'number')).toBe(10);
+      expect(manager.getString('test', 'string')).toBe('Hello, world!');
+      expect(manager.getObject('test', 'object')).toEqual({'one': 1, 'two': 2, 'three': 3});
+
+      expect(manager.getString('test', 'string-placeholder', {'from': 'Bob', 'to': 'Max'}))
+        .toBe('Hello Max, my name is Bob.');
+    });
+  });
+};
diff --git a/test/test_main.js b/test/test_main.js
index c355e7c..31854b5 100644
--- a/test/test_main.js
+++ b/test/test_main.js
@@ -7,6 +7,7 @@ const collectionsMain = goog.require('test.clulib.collections');
 const domMain = goog.require('test.clulib.dom');
 const functionsMain = goog.require('test.clulib.functions');
 const resourceBundleMain = goog.require('test.clulib.l10n.ResourceBundle');
+const resourceManagerMain = goog.require('test.clulib.l10n.ResourceManager');
 const httpRequestMain = goog.require('test.clulib.net.http_request');
 const mathMain = goog.require('test.clulib.math');
 
@@ -17,5 +18,6 @@ collectionsMain();
 domMain();
 functionsMain();
 resourceBundleMain();
+resourceManagerMain();
 httpRequestMain();
 mathMain();