diff --git a/js/components/pages/page-settings.js b/js/components/pages/page-settings.js
index dd569cc..6e42690 100644
--- a/js/components/pages/page-settings.js
+++ b/js/components/pages/page-settings.js
@@ -85,6 +85,15 @@ class PageSettings extends HTMLElement {
             }
         })
 
+        // Delete all local data
+        this.querySelector('#clear-all-data')?.addEventListener('click', async () => {
+            if (confirm(t('settings.confirmDeleteAll'))) {
+                await auth.clearAllData()
+                window.location.hash = '#/'
+                window.location.reload()
+            }
+        })
+
         // Toggle UUID visibility
         this.querySelector('#toggle-uid-btn')?.addEventListener('click', () => {
             this.uidVisible = !this.uidVisible
@@ -292,6 +301,16 @@ class PageSettings extends HTMLElement {
                                 ${t('settings.clear')}
                             </button>
                         </div>
+
+                        <div class="setting-item">
+                            <div>
+                                <label>${t('settings.deleteAllData')}</label>
+                                <p class="setting-hint">${t('settings.deleteAllDataHint')}</p>
+                            </div>
+                            <button id="clear-all-data" class="btn btn-outline btn-sm btn-danger">
+                                ${t('settings.deleteAll')}
+                            </button>
+                        </div>
                     </section>
 
                     <!-- About -->
diff --git a/js/services/auth.js b/js/services/auth.js
index 66a6e2c..ad656b9 100644
--- a/js/services/auth.js
+++ b/js/services/auth.js
@@ -149,6 +149,30 @@ class AuthService {
         this.notifyListeners()
     }
 
+    /**
+     * Clears all local data (tokens, keys, caches, preferences)
+     */
+    async clearAllData() {
+        await this.logout()
+        cryptoService.destroyKeyPair()
+
+        const keysToRemove = []
+        for (let i = 0; i < localStorage.length; i++) {
+            const key = localStorage.key(i)
+            if (key && key.startsWith('dgray_')) keysToRemove.push(key)
+        }
+        keysToRemove.forEach(k => localStorage.removeItem(k))
+
+        localStorage.removeItem('searchFilters')
+        localStorage.removeItem('locale')
+        localStorage.removeItem('theme')
+
+        for (let i = sessionStorage.length - 1; i >= 0; i--) {
+            const key = sessionStorage.key(i)
+            if (key && key.startsWith('dgray_')) sessionStorage.removeItem(key)
+        }
+    }
+
     /**
      * Reset preferences to defaults on logout
      */
diff --git a/js/services/crypto.js b/js/services/crypto.js
index a99fe26..82ba6fa 100644
--- a/js/services/crypto.js
+++ b/js/services/crypto.js
@@ -140,6 +140,12 @@ class CryptoService {
         this.keyPair = null
     }
 
+    destroyKeyPair() {
+        this.keyPair = null
+        localStorage.removeItem(STORAGE_KEY)
+        localStorage.removeItem(SALT_KEY)
+    }
+
     getPublicKey() {
         if (!this.keyPair) return null
         return this.naclUtil.encodeBase64(this.keyPair.publicKey)
diff --git a/locales/de.json b/locales/de.json
index 2d076d2..0d3918f 100644
--- a/locales/de.json
+++ b/locales/de.json
@@ -278,7 +278,11 @@
     "searchCleared": "Suchverlauf gelöscht",
     "about": "Über",
     "currency": "Währung",
-    "currencyChanged": "Währung geändert"
+    "currencyChanged": "Währung geändert",
+    "deleteAllData": "Alle lokalen Daten löschen",
+    "deleteAllDataHint": "Entfernt alle gespeicherten Daten aus diesem Browser, einschließlich Verschlüsselungsschlüssel, Favoriten und Einstellungen. Chat-Verläufe können nicht wiederhergestellt werden.",
+    "deleteAll": "Alles löschen",
+    "confirmDeleteAll": "Alle lokalen Daten löschen? Verschlüsselungsschlüssel gehen verloren und Chat-Nachrichten können nicht wiederhergestellt werden."
   },
   "notifications": {
     "title": "Benachrichtigungen",
diff --git a/locales/en.json b/locales/en.json
index 1a91a88..b773ea9 100644
--- a/locales/en.json
+++ b/locales/en.json
@@ -278,7 +278,11 @@
     "searchCleared": "Search history deleted",
     "about": "About",
     "currency": "Currency",
-    "currencyChanged": "Currency changed"
+    "currencyChanged": "Currency changed",
+    "deleteAllData": "Delete all local data",
+    "deleteAllDataHint": "Removes all saved data from this browser including encryption keys, favorites, and preferences. Chat history cannot be recovered.",
+    "deleteAll": "Delete all",
+    "confirmDeleteAll": "Delete all local data? Encryption keys will be lost and chat messages cannot be recovered."
   },
   "notifications": {
     "title": "Notifications",
diff --git a/locales/es.json b/locales/es.json
index 861117e..865e756 100644
--- a/locales/es.json
+++ b/locales/es.json
@@ -278,7 +278,11 @@
     "searchCleared": "Historial de búsqueda eliminado",
     "about": "Acerca de",
     "currency": "Moneda",
-    "currencyChanged": "Moneda cambiada"
+    "currencyChanged": "Moneda cambiada",
+    "deleteAllData": "Eliminar todos los datos locales",
+    "deleteAllDataHint": "Elimina todos los datos guardados de este navegador, incluidas las claves de cifrado, favoritos y preferencias. El historial de chat no se puede recuperar.",
+    "deleteAll": "Eliminar todo",
+    "confirmDeleteAll": "¿Eliminar todos los datos locales? Las claves de cifrado se perderán y los mensajes no se podrán recuperar."
   },
   "notifications": {
     "title": "Notificaciones",
diff --git a/locales/fr.json b/locales/fr.json
index c0bf23b..b99a499 100644
--- a/locales/fr.json
+++ b/locales/fr.json
@@ -278,7 +278,11 @@
     "searchCleared": "Historique de recherche supprimé",
     "about": "À propos",
     "currency": "Devise",
-    "currencyChanged": "Devise modifiée"
+    "currencyChanged": "Devise modifiée",
+    "deleteAllData": "Supprimer toutes les données locales",
+    "deleteAllDataHint": "Supprime toutes les données enregistrées de ce navigateur, y compris les clés de chiffrement, les favoris et les préférences. L'historique des conversations ne peut pas être récupéré.",
+    "deleteAll": "Tout supprimer",
+    "confirmDeleteAll": "Supprimer toutes les données locales ? Les clés de chiffrement seront perdues et les messages ne pourront pas être récupérés."
   },
   "notifications": {
     "title": "Notifications",
diff --git a/locales/it.json b/locales/it.json
index 4bb9006..6ec4b98 100644
--- a/locales/it.json
+++ b/locales/it.json
@@ -278,7 +278,11 @@
     "searchCleared": "Cronologia ricerche eliminata",
     "about": "Informazioni",
     "currency": "Valuta",
-    "currencyChanged": "Valuta cambiata"
+    "currencyChanged": "Valuta cambiata",
+    "deleteAllData": "Elimina tutti i dati locali",
+    "deleteAllDataHint": "Rimuove tutti i dati salvati da questo browser, incluse le chiavi di crittografia, i preferiti e le impostazioni. La cronologia delle chat non può essere recuperata.",
+    "deleteAll": "Elimina tutto",
+    "confirmDeleteAll": "Eliminare tutti i dati locali? Le chiavi di crittografia andranno perse e i messaggi non potranno essere recuperati."
   },
   "notifications": {
     "title": "Notifiche",
diff --git a/locales/pt.json b/locales/pt.json
index 6110bd0..407a1d0 100644
--- a/locales/pt.json
+++ b/locales/pt.json
@@ -278,7 +278,11 @@
     "searchCleared": "Histórico de busca excluído",
     "about": "Sobre",
     "currency": "Moeda",
-    "currencyChanged": "Moeda alterada"
+    "currencyChanged": "Moeda alterada",
+    "deleteAllData": "Excluir todos os dados locais",
+    "deleteAllDataHint": "Remove todos os dados salvos deste navegador, incluindo chaves de criptografia, favoritos e preferências. O histórico de conversas não pode ser recuperado.",
+    "deleteAll": "Excluir tudo",
+    "confirmDeleteAll": "Excluir todos os dados locais? As chaves de criptografia serão perdidas e as mensagens não poderão ser recuperadas."
   },
   "notifications": {
     "title": "Notificações",
diff --git a/locales/ru.json b/locales/ru.json
index a80810e..2a60ea3 100644
--- a/locales/ru.json
+++ b/locales/ru.json
@@ -278,7 +278,11 @@
     "searchCleared": "История поиска удалена",
     "about": "О приложении",
     "currency": "Валюта",
-    "currencyChanged": "Валюта изменена"
+    "currencyChanged": "Валюта изменена",
+    "deleteAllData": "Удалить все локальные данные",
+    "deleteAllDataHint": "Удаляет все сохранённые данные из этого браузера, включая ключи шифрования, избранное и настройки. История чата не может быть восстановлена.",
+    "deleteAll": "Удалить всё",
+    "confirmDeleteAll": "Удалить все локальные данные? Ключи шифрования будут утеряны, а сообщения чата невозможно будет восстановить."
   },
   "notifications": {
     "title": "Уведомления",