diff --git a/public/scripts/extensions.js b/public/scripts/extensions.js
index a197e3a41..aa8d658e8 100644
--- a/public/scripts/extensions.js
+++ b/public/scripts/extensions.js
@@ -7,7 +7,7 @@ import { renderTemplate, renderTemplateAsync } from './templates.js';
 import { delay, isSubsetOf, sanitizeSelector, setValueByPath } from './utils.js';
 import { getContext } from './st-context.js';
 import { isAdmin } from './user.js';
-import { t } from './i18n.js';
+import { addLocaleData, getCurrentLocale, t } from './i18n.js';
 import { debounce_timeout } from './constants.js';
 import { accountStorage } from './util/AccountStorage.js';
 
@@ -384,7 +384,7 @@ async function activateExtensions() {
         if (meetsModuleRequirements && !isDisabled) {
             try {
                 console.debug('Activating extension', name);
-                const promise = Promise.all([addExtensionScript(name, manifest), addExtensionStyle(name, manifest)]);
+                const promise = Promise.all([addExtensionScript(name, manifest), addExtensionStyle(name, manifest), addExtensionLocale(name, manifest)]);
                 await promise
                     .then(() => activeExtensions.add(name))
                     .catch(err => console.log('Could not activate extension', name, err));
@@ -576,6 +576,42 @@ function addExtensionScript(name, manifest) {
     });
 }
 
+/**
+ * Adds a localization data for an extension.
+ * @param {string} name Extension name
+ * @param {object} manifest Manifest object
+ */
+function addExtensionLocale(name, manifest) {
+    // No i18n data in the manifest
+    if (!manifest.i18n || typeof manifest.i18n !== 'object') {
+        return Promise.resolve();
+    }
+
+    const currentLocale = getCurrentLocale();
+    const localeFile = manifest.i18n[currentLocale];
+
+    // Manifest doesn't provide a locale file for the current locale
+    if (!localeFile) {
+        return Promise.resolve();
+    }
+
+    return fetch(`/scripts/extensions/${name}/${localeFile}`)
+        .then(async response => {
+            if (!response.ok) {
+                throw new Error(`HTTP ${response.status}: ${response.statusText}`);
+            }
+
+            const data = await response.json();
+
+            if (data && typeof data === 'object') {
+                addLocaleData(currentLocale, data);
+            }
+        })
+        .catch(err => {
+            console.log('Could not load extension locale data for ' + name, err);
+        });
+}
+
 /**
  * Generates HTML string for displaying an extension in the UI.
  *
diff --git a/public/scripts/i18n.js b/public/scripts/i18n.js
index 39dccda4d..9dd213b04 100644
--- a/public/scripts/i18n.js
+++ b/public/scripts/i18n.js
@@ -11,6 +11,30 @@ var localeData;
 
 export const getCurrentLocale = () => localeFile;
 
+/**
+ * Adds additional localization data to the current locale file.
+ * @param {string} localeId Locale ID (e.g. 'fr-fr' or 'zh-cn')
+ * @param {Record<string, string>} data Localization data to add
+ */
+export function addLocaleData(localeId, data) {
+    if (!localeData) {
+        console.warn('Localization data not loaded yet. Additional data will not be added.');
+        return;
+    }
+
+    if (localeId !== localeFile) {
+        console.debug('Ignoring addLocaleData call for different locale', localeId);
+        return;
+    }
+
+    for (const [key, value] of Object.entries(data)) {
+        // Overrides for default locale data are not allowed
+        if (!Object.hasOwn(localeData, key)) {
+            localeData[key] = value;
+        }
+    }
+}
+
 /**
  * An observer that will check if any new i18n elements are added to the document
  * @type {MutationObserver}
diff --git a/public/scripts/st-context.js b/public/scripts/st-context.js
index 2393a4800..ad7021622 100644
--- a/public/scripts/st-context.js
+++ b/public/scripts/st-context.js
@@ -54,7 +54,7 @@ import {
     writeExtensionField,
 } from './extensions.js';
 import { groups, openGroupChat, selected_group } from './group-chats.js';
-import { t, translate } from './i18n.js';
+import { addLocaleData, getCurrentLocale, t, translate } from './i18n.js';
 import { hideLoader, showLoader } from './loader.js';
 import { MacrosParser } from './macros.js';
 import { getChatCompletionModel, oai_settings } from './openai.js';
@@ -165,6 +165,8 @@ export function getContext() {
         isMobile,
         t,
         translate,
+        getCurrentLocale,
+        addLocaleData,
         tags,
         tagMap: tag_map,
         menuType: menu_type,