diff --git a/.env.example b/.env.example
index ece51f9..2c30e82 100644
--- a/.env.example
+++ b/.env.example
@@ -10,6 +10,8 @@ VUE_APP_TITLE=irandom
 VUE_APP_BRAND_URL=https://git.imiheev.online/admin/irandom
 # Logo path or absolute URL (file should be in public/ if relative)
 VUE_APP_LOGO_URL=/logo.png
+# Default UI language: ru | en (overridden by localStorage after user chooses)
+VUE_APP_DEFAULT_LOCALE=ru
 
 # Theme colors (CSS hex)
 VUE_APP_COLOR_PRIMARY=#c9a66b
diff --git a/package-lock.json b/package-lock.json
index b2773fa..a362b0c 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -11,6 +11,7 @@
         "@element-plus/icons-vue": "^2.3.2",
         "element-plus": "^2.14.3",
         "vue": "^3.5.13",
+        "vue-i18n": "^11.4.8",
         "vue-router": "^4.6.4"
       },
       "devDependencies": {
@@ -653,6 +654,67 @@
       "dev": true,
       "license": "BSD-3-Clause"
     },
+    "node_modules/@intlify/core-base": {
+      "version": "11.4.8",
+      "resolved": "https://registry.npmjs.org/@intlify/core-base/-/core-base-11.4.8.tgz",
+      "integrity": "sha512-A+Q7SKm5oEcy1E/cghqd7n/St4XjTqLhiiyDuieNcMrJcrHlkY5n0jp7Q9dD3txvVHzvsmBVV5M9wD5/s1zfzw==",
+      "license": "MIT",
+      "dependencies": {
+        "@intlify/devtools-types": "11.4.8",
+        "@intlify/message-compiler": "11.4.8",
+        "@intlify/shared": "11.4.8"
+      },
+      "engines": {
+        "node": ">= 22"
+      },
+      "funding": {
+        "url": "https://github.com/sponsors/kazupon"
+      }
+    },
+    "node_modules/@intlify/devtools-types": {
+      "version": "11.4.8",
+      "resolved": "https://registry.npmjs.org/@intlify/devtools-types/-/devtools-types-11.4.8.tgz",
+      "integrity": "sha512-MGpID+rlfzGUbNcnC20bm5NMSBHPrvx0atLTfv9dftn3kjXw1hGKDcIcwrO99tSrZEc2i+hczRL7ks8qXsHPkQ==",
+      "license": "MIT",
+      "dependencies": {
+        "@intlify/core-base": "11.4.8",
+        "@intlify/shared": "11.4.8"
+      },
+      "engines": {
+        "node": ">= 22"
+      },
+      "funding": {
+        "url": "https://github.com/sponsors/kazupon"
+      }
+    },
+    "node_modules/@intlify/message-compiler": {
+      "version": "11.4.8",
+      "resolved": "https://registry.npmjs.org/@intlify/message-compiler/-/message-compiler-11.4.8.tgz",
+      "integrity": "sha512-vbzk17dYwduYiv52EK61+FDCyhfVg1uPUtPmiD/d45W99uJIcXywrweOBcHv7n9/iEqmXiMGT52bgJbZDQqK3w==",
+      "license": "MIT",
+      "dependencies": {
+        "@intlify/shared": "11.4.8",
+        "source-map-js": "^1.0.2"
+      },
+      "engines": {
+        "node": ">= 22"
+      },
+      "funding": {
+        "url": "https://github.com/sponsors/kazupon"
+      }
+    },
+    "node_modules/@intlify/shared": {
+      "version": "11.4.8",
+      "resolved": "https://registry.npmjs.org/@intlify/shared/-/shared-11.4.8.tgz",
+      "integrity": "sha512-XbRgrv+XEuvDr7UCY55oibVrh+o4u+A0VB6nSL0F5Z8LcZxE/8j573LYG6bCrOigIcHdGpSNI7Rh5UpC5/B/eg==",
+      "license": "MIT",
+      "engines": {
+        "node": ">= 22"
+      },
+      "funding": {
+        "url": "https://github.com/sponsors/kazupon"
+      }
+    },
     "node_modules/@jridgewell/sourcemap-codec": {
       "version": "1.5.5",
       "resolved": "https://registry.npmjs.org/@jridgewell/sourcemap-codec/-/sourcemap-codec-1.5.5.tgz",
@@ -3201,6 +3263,27 @@
         "eslint": ">=6.0.0"
       }
     },
+    "node_modules/vue-i18n": {
+      "version": "11.4.8",
+      "resolved": "https://registry.npmjs.org/vue-i18n/-/vue-i18n-11.4.8.tgz",
+      "integrity": "sha512-0ULeHP6Z9CGvAm67S77ZEp41cfGXIREGL8qfhos2BMgcQQewtQcDKuojt6jjasAD/S8GwfTp2ySPmDSpwvrCMQ==",
+      "license": "MIT",
+      "dependencies": {
+        "@intlify/core-base": "11.4.8",
+        "@intlify/devtools-types": "11.4.8",
+        "@intlify/shared": "11.4.8",
+        "@vue/devtools-api": "^6.5.0"
+      },
+      "engines": {
+        "node": ">= 22"
+      },
+      "funding": {
+        "url": "https://github.com/sponsors/kazupon"
+      },
+      "peerDependencies": {
+        "vue": "^3.0.0"
+      }
+    },
     "node_modules/vue-router": {
       "version": "4.6.4",
       "resolved": "https://registry.npmjs.org/vue-router/-/vue-router-4.6.4.tgz",
diff --git a/package.json b/package.json
index ed867c9..e5d9f5d 100644
--- a/package.json
+++ b/package.json
@@ -17,6 +17,7 @@
     "@element-plus/icons-vue": "^2.3.2",
     "element-plus": "^2.14.3",
     "vue": "^3.5.13",
+    "vue-i18n": "^11.4.8",
     "vue-router": "^4.6.4"
   },
   "devDependencies": {
diff --git a/public/config.js b/public/config.js
index 87054a4..d1637fe 100644
--- a/public/config.js
+++ b/public/config.js
@@ -4,6 +4,7 @@ window.__APP_CONFIG__ = {
   "title": "irandom",
   "brandUrl": "https://git.imiheev.online/admin/irandom",
   "logoUrl": "/logo.png",
+  "defaultLocale": "ru",
   "colors": {
     "primary": "#c9a66b",
     "accent": "#e6c566",
diff --git a/scripts/generate-config.js b/scripts/generate-config.js
index 1ac1e8d..4512e35 100644
--- a/scripts/generate-config.js
+++ b/scripts/generate-config.js
@@ -10,6 +10,7 @@ const DEFAULTS = {
   VUE_APP_TITLE: 'irandom',
   VUE_APP_BRAND_URL: 'https://git.imiheev.online/admin/irandom',
   VUE_APP_LOGO_URL: '/logo.png',
+  VUE_APP_DEFAULT_LOCALE: 'ru',
   VUE_APP_COLOR_PRIMARY: '#c9a66b',
   VUE_APP_COLOR_ACCENT: '#e6c566',
   VUE_APP_COLOR_BG: '#1a1815',
@@ -63,6 +64,7 @@ function buildConfig(env) {
     title: pick('VUE_APP_TITLE'),
     brandUrl: pick('VUE_APP_BRAND_URL'),
     logoUrl: pick('VUE_APP_LOGO_URL'),
+    defaultLocale: pick('VUE_APP_DEFAULT_LOCALE'),
     colors: {
       primary: pick('VUE_APP_COLOR_PRIMARY'),
       accent: pick('VUE_APP_COLOR_ACCENT'),
diff --git a/src/App.vue b/src/App.vue
index 859abe6..b562e64 100644
--- a/src/App.vue
+++ b/src/App.vue
@@ -1,23 +1,28 @@
 <template>
-  <el-container class="app-shell">
-    <el-aside width="220px" class="aside desktop-aside">
-      <ModeSidebar show-brand />
-    </el-aside>
-    <el-container class="main-column">
-      <el-header height="auto" class="header mobile-header">
-        <AppHeader />
-      </el-header>
-      <el-main class="main">
-        <RouterView />
-      </el-main>
+  <el-config-provider :locale="elementLocale">
+    <el-container class="app-shell">
+      <el-aside :width="asideWidth" class="aside desktop-aside">
+        <ModeSidebar show-brand @collapse-change="onCollapseChange" />
+      </el-aside>
+      <el-container class="main-column">
+        <el-header height="auto" class="header mobile-header">
+          <AppHeader />
+        </el-header>
+        <el-main class="main">
+          <RouterView />
+        </el-main>
+      </el-container>
+      <nav class="mobile-toolbar" :aria-label="$t('nav.modes')">
+        <ModeSidebar />
+      </nav>
     </el-container>
-    <nav class="mobile-toolbar" aria-label="Режимы генерации">
-      <ModeSidebar />
-    </nav>
-  </el-container>
+  </el-config-provider>
 </template>
 
 <script>
+import { useI18n } from 'vue-i18n'
+import ru from 'element-plus/es/locale/lang/ru'
+import en from 'element-plus/es/locale/lang/en'
 import AppHeader from './components/AppHeader.vue'
 import ModeSidebar from './components/ModeSidebar.vue'
 
@@ -26,6 +31,28 @@ export default {
   components: {
     AppHeader,
     ModeSidebar
+  },
+  setup() {
+    const { locale } = useI18n()
+    return { locale }
+  },
+  data() {
+    return {
+      sidebarCollapsed: false
+    }
+  },
+  computed: {
+    elementLocale() {
+      return this.locale === 'en' ? en : ru
+    },
+    asideWidth() {
+      return this.sidebarCollapsed ? '64px' : '220px'
+    }
+  },
+  methods: {
+    onCollapseChange(collapsed) {
+      this.sidebarCollapsed = collapsed
+    }
   }
 }
 </script>
@@ -40,6 +67,7 @@ export default {
   background: var(--ir-surface);
   overflow: hidden;
   padding: 0;
+  transition: width 0.2s ease;
 
   .mode-sidebar {
     height: 100%;
@@ -68,6 +96,11 @@ export default {
   display: none;
 }
 
+.ir-lang-popper {
+  background: var(--ir-surface) !important;
+  border: 1px solid var(--ir-border) !important;
+}
+
 @media (max-width: 424px) {
   .app-shell {
     flex-direction: column !important;
diff --git a/src/components/ModeSidebar.vue b/src/components/ModeSidebar.vue
index 8a17534..df576e4 100644
--- a/src/components/ModeSidebar.vue
+++ b/src/components/ModeSidebar.vue
@@ -1,5 +1,5 @@
 <template>
-  <nav class="mode-sidebar" aria-label="Режимы генерации">
+  <nav class="mode-sidebar" :class="{ collapsed: isCollapsed && !isMobile }" :aria-label="t('nav.modes')">
     <a
       v-if="showBrand"
       class="brand"
@@ -8,33 +8,84 @@
       rel="noopener noreferrer"
     >
       <img class="logo" :src="config.logoUrl" :alt="config.name" />
-      <span class="brand-name">{{ config.name }}</span>
+      <span v-show="!isCollapsed || isMobile" class="brand-name">{{ config.name }}</span>
     </a>
-    <RouterLink
-      v-for="mode in modes"
-      :key="mode.id"
-      :to="mode.to"
-      class="mode-item"
-      active-class="active"
+
+    <button
+      v-if="showBrand && !isMobile"
+      type="button"
+      class="collapse-btn"
+      :title="isCollapsed ? t('nav.expand') : t('nav.collapse')"
+      :aria-label="isCollapsed ? t('nav.expand') : t('nav.collapse')"
+      @click="toggleCollapse"
     >
-      <el-icon class="mode-icon" :size="22">
-        <component :is="mode.icon" />
+      <el-icon :size="18">
+        <Fold v-if="!isCollapsed" />
+        <Expand v-else />
       </el-icon>
-      <span class="mode-label">{{ mode.label }}</span>
-    </RouterLink>
+    </button>
+
+    <el-menu
+      class="side-menu"
+      :key="activeIndex + '-' + locale"
+      :collapse="isCollapsed && !isMobile"
+      :collapse-transition="false"
+      :default-active="activeIndex"
+      background-color="transparent"
+      text-color="var(--ir-text-muted)"
+      active-text-color="var(--ir-primary)"
+      @select="onMenuSelect"
+    >
+      <el-menu-item
+        v-for="mode in modes"
+        :key="mode.id"
+        :index="mode.to"
+      >
+        <el-icon>
+          <component :is="mode.icon" />
+        </el-icon>
+        <template #title>{{ t(mode.labelKey) }}</template>
+      </el-menu-item>
+
+      <el-sub-menu index="language" popper-class="ir-lang-popper">
+        <template #title>
+          <el-icon><Flag /></el-icon>
+          <span>{{ t('nav.language') }}</span>
+        </template>
+        <el-menu-item
+          index="lang-ru"
+          :class="{ 'is-locale-active': locale === 'ru' }"
+        >
+          {{ t('lang.ru') }}
+        </el-menu-item>
+        <el-menu-item
+          index="lang-en"
+          :class="{ 'is-locale-active': locale === 'en' }"
+        >
+          {{ t('lang.en') }}
+        </el-menu-item>
+      </el-sub-menu>
+    </el-menu>
   </nav>
 </template>
 
 <script>
-import { Histogram, List, Coin } from '@element-plus/icons-vue'
+import { Histogram, List, Coin, Fold, Expand, Flag } from '@element-plus/icons-vue'
+import { useI18n } from 'vue-i18n'
 import { getAppConfig } from '@/config/appConfig'
+import i18n, { setAppLocale } from '@/i18n'
+
+const COLLAPSE_KEY = 'irandom:sidebar-collapsed'
 
 export default {
   name: 'ModeSidebar',
   components: {
     Histogram,
     List,
-    Coin
+    Coin,
+    Fold,
+    Expand,
+    Flag
   },
   props: {
     showBrand: {
@@ -42,15 +93,76 @@ export default {
       default: false
     }
   },
+  emits: ['collapse-change'],
+  setup() {
+    const { t, locale } = useI18n()
+    return { t, locale }
+  },
   data() {
     return {
       config: getAppConfig(),
+      isCollapsed: false,
+      isMobile: false,
       modes: [
-        { id: 'range', to: '/range', label: 'Диапазон', icon: 'Histogram' },
-        { id: 'list', to: '/list', label: 'Список', icon: 'List' },
-        { id: 'coin', to: '/coin', label: 'Орёл / решка', icon: 'Coin' }
+        { id: 'range', to: '/range', labelKey: 'nav.range', icon: 'Histogram' },
+        { id: 'list', to: '/list', labelKey: 'nav.list', icon: 'List' },
+        { id: 'coin', to: '/coin', labelKey: 'nav.coin', icon: 'Coin' }
       ]
     }
+  },
+  computed: {
+    activeIndex() {
+      return this.$route.path
+    }
+  },
+  created() {
+    this.isCollapsed = this.readCollapsed()
+  },
+  mounted() {
+    this.updateMobile()
+    window.addEventListener('resize', this.updateMobile)
+    this.$emit('collapse-change', this.isCollapsed && !this.isMobile)
+  },
+  beforeUnmount() {
+    window.removeEventListener('resize', this.updateMobile)
+  },
+  methods: {
+    readCollapsed() {
+      try {
+        return localStorage.getItem(COLLAPSE_KEY) === '1'
+      } catch {
+        return false
+      }
+    },
+    persistCollapsed() {
+      try {
+        localStorage.setItem(COLLAPSE_KEY, this.isCollapsed ? '1' : '0')
+      } catch {
+        // ignore
+      }
+    },
+    toggleCollapse() {
+      this.isCollapsed = !this.isCollapsed
+      this.persistCollapsed()
+      this.$emit('collapse-change', this.isCollapsed && !this.isMobile)
+    },
+    updateMobile() {
+      this.isMobile = window.matchMedia('(max-width: 424px)').matches
+      this.$emit('collapse-change', this.isCollapsed && !this.isMobile)
+    },
+    onMenuSelect(index) {
+      if (index === 'lang-ru') {
+        setAppLocale(i18n, 'ru')
+        return
+      }
+      if (index === 'lang-en') {
+        setAppLocale(i18n, 'en')
+        return
+      }
+      if (index.startsWith('/') && this.$route.path !== index) {
+        this.$router.push(index)
+      }
+    }
   }
 }
 </script>
@@ -59,9 +171,9 @@ export default {
 .mode-sidebar {
   display: flex;
   flex-direction: column;
-  gap: 0.5rem;
+  gap: 0.35rem;
   height: 100%;
-  padding: 1rem 0.75rem;
+  padding: 1rem 0.5rem;
   background: var(--ir-surface);
   border-right: 1px solid var(--ir-border);
 }
@@ -70,10 +182,11 @@ export default {
   display: flex;
   align-items: center;
   gap: 0.65rem;
-  padding: 0.35rem 0.5rem 1rem;
-  margin-bottom: 0.25rem;
+  padding: 0.35rem 0.5rem 0.85rem;
+  margin-bottom: 0.15rem;
   border-bottom: 1px solid var(--ir-border);
   text-decoration: none;
+  overflow: hidden;
 }
 
 .logo {
@@ -90,93 +203,120 @@ export default {
   letter-spacing: 0.02em;
   color: var(--ir-primary);
   transition: color 0.15s ease;
+  white-space: nowrap;
 }
 
 .brand:hover .brand-name {
   color: color-mix(in srgb, var(--ir-primary) 70%, white);
 }
 
-.mode-item {
-  display: flex;
-  align-items: center;
-  gap: 0.65rem;
+.collapse-btn {
+  align-self: flex-end;
   appearance: none;
   border: 1px solid transparent;
   border-radius: 8px;
   background: transparent;
   color: var(--ir-text-muted);
-  padding: 0.85rem 0.75rem;
-  text-align: left;
-  text-decoration: none;
-  font: inherit;
-  font-size: 0.95rem;
+  padding: 0.45rem;
   cursor: pointer;
-  transition: background 0.15s ease, color 0.15s ease, border-color 0.15s ease;
+  transition: background 0.15s ease, color 0.15s ease;
 
   &:hover {
     background: var(--ir-surface-raised);
     color: var(--ir-text);
   }
-
-  &.active {
-    background: rgba(var(--ir-primary-rgb), 0.18);
-    border-color: var(--ir-primary);
-    color: var(--ir-primary);
-    font-weight: 600;
-  }
 }
 
-.mode-icon {
-  flex-shrink: 0;
+.side-menu {
+  border-right: none !important;
+  width: 100%;
+  background: transparent !important;
+  flex: 1;
+}
+
+.side-menu:not(.el-menu--collapse) {
+  width: 100%;
+}
+
+:deep(.el-menu-item),
+:deep(.el-sub-menu__title) {
+  border-radius: 8px;
+  margin: 0.15rem 0;
+  height: 44px;
+  line-height: 44px;
+}
+
+:deep(.el-menu-item.is-active) {
+  background: rgba(var(--ir-primary-rgb), 0.18) !important;
+  border: 1px solid var(--ir-primary);
+  font-weight: 600;
+}
+
+:deep(.el-menu-item:hover),
+:deep(.el-sub-menu__title:hover) {
+  background: var(--ir-surface-raised) !important;
+}
+
+:deep(.el-menu-item.is-locale-active) {
+  color: var(--ir-primary) !important;
+  font-weight: 600;
+}
+
+.collapsed {
+  .brand {
+    justify-content: center;
+    padding-left: 0.25rem;
+    padding-right: 0.25rem;
+  }
+
+  .collapse-btn {
+    align-self: center;
+  }
 }
 
 @media (max-width: 424px) {
   .mode-sidebar {
     flex-direction: row;
     align-items: stretch;
-    justify-content: space-around;
-    gap: 0;
     height: auto;
-    padding: 0.35rem 0.25rem calc(0.35rem + env(safe-area-inset-bottom, 0px));
+    padding: 0.2rem 0.15rem calc(0.2rem + env(safe-area-inset-bottom, 0px));
     border-right: none;
     border-top: 1px solid var(--ir-border);
     box-shadow: 0 -4px 20px rgba(0, 0, 0, 0.35);
+    gap: 0;
   }
 
-  .mode-item {
+  .side-menu {
+    display: flex;
+    flex-direction: row;
+    width: 100%;
+    justify-content: space-around;
+  }
+
+  :deep(.el-menu-item),
+  :deep(.el-sub-menu) {
     flex: 1;
+  }
+
+  :deep(.el-menu-item),
+  :deep(.el-sub-menu__title) {
+    display: flex;
     flex-direction: column;
+    align-items: center;
     justify-content: center;
-    gap: 0.2rem;
-    padding: 0.55rem 0.25rem;
-    border-radius: 10px;
-    text-align: center;
-    font-size: 0.7rem;
-    border-color: transparent;
-    background: transparent;
-
-    &:hover {
-      background: transparent;
-      color: var(--ir-text);
-    }
-
-    &.active {
-      background: transparent;
-      border-color: transparent;
-      color: var(--ir-primary);
-    }
-  }
-
-  .mode-icon {
-    font-size: 1.35rem;
-  }
-
-  .mode-label {
+    height: auto;
     line-height: 1.2;
-    max-width: 100%;
-    overflow: hidden;
-    text-overflow: ellipsis;
-    white-space: nowrap;
+    padding: 0.45rem 0.2rem !important;
+    border: none !important;
+    font-size: 0.65rem;
+  }
+
+  :deep(.el-menu-item.is-active) {
+    background: transparent !important;
+  }
+
+  :deep(.el-sub-menu .el-sub-menu__icon-arrow) {
+    display: none;
   }
 }
 </style>
diff --git a/src/components/ResultDisplay.vue b/src/components/ResultDisplay.vue
index f7a2e26..2d9b035 100644
--- a/src/components/ResultDisplay.vue
+++ b/src/components/ResultDisplay.vue
@@ -1,6 +1,6 @@
 <template>
   <div class="result-display">
-    <div class="result-label">Результат</div>
+    <div class="result-label">{{ t('result.label') }}</div>
     <div v-if="hasResult" class="result-value">
       <template v-if="Array.isArray(result)">
         <span v-for="(item, index) in result" :key="index" class="result-chip">
@@ -11,11 +11,13 @@
         {{ result }}
       </template>
     </div>
-    <div v-else class="result-empty">Нажмите «Сгенерировать»</div>
+    <div v-else class="result-empty">{{ t('result.empty') }}</div>
   </div>
 </template>
 
 <script>
+import { useI18n } from 'vue-i18n'
+
 export default {
   name: 'ResultDisplay',
   props: {
@@ -24,6 +26,10 @@ export default {
       default: null
     }
   },
+  setup() {
+    const { t } = useI18n()
+    return { t }
+  },
   computed: {
     hasResult() {
       if (this.result === null || this.result === undefined || this.result === '') {
diff --git a/src/components/generators/CoinGenerator.vue b/src/components/generators/CoinGenerator.vue
index 864a08f..6f90906 100644
--- a/src/components/generators/CoinGenerator.vue
+++ b/src/components/generators/CoinGenerator.vue
@@ -1,17 +1,18 @@
 <template>
   <el-form label-position="top" class="generator-form" @submit.prevent="onGenerate">
-    <el-form-item label="Количество бросков">
+    <el-form-item :label="t('coin.flips')">
       <el-input-number v-model="count" :min="1" :max="100" :controls="true" />
     </el-form-item>
-    <p class="hint">Каждый бросок даёт «орёл» или «решку».</p>
+    <p class="hint">{{ t('coin.hint') }}</p>
     <el-button type="primary" native-type="submit" size="large">
-      Сгенерировать
+      {{ t('coin.generate') }}
     </el-button>
   </el-form>
 </template>
 
 <script>
 import { ElMessage } from 'element-plus'
+import { useI18n } from 'vue-i18n'
 import { flipCoin } from '@/utils/random'
 import { loadFormState, saveFormState } from '@/utils/persistForm'
 
@@ -23,6 +24,10 @@ const DEFAULTS = {
 export default {
   name: 'CoinGenerator',
   emits: ['result'],
+  setup() {
+    const { t } = useI18n()
+    return { t }
+  },
   data() {
     return loadFormState(STORAGE_KEY, DEFAULTS)
   },
@@ -37,10 +42,10 @@ export default {
     },
     onGenerate() {
       if (this.count < 1) {
-        ElMessage.error('Количество должно быть не меньше 1')
+        ElMessage.error(this.t('coin.errCount'))
         return
       }
-      const flips = flipCoin(this.count)
+      const flips = flipCoin(this.count).map((side) => this.t(`coin.${side}`))
       this.$emit('result', this.count === 1 ? flips[0] : flips)
     }
   }
diff --git a/src/components/generators/ListGenerator.vue b/src/components/generators/ListGenerator.vue
index e0a4216..9a4d7ec 100644
--- a/src/components/generators/ListGenerator.vue
+++ b/src/components/generators/ListGenerator.vue
@@ -1,27 +1,28 @@
 <template>
   <el-form label-position="top" class="generator-form" @submit.prevent="onGenerate">
-    <el-form-item label="Список значений (по одному на строку)">
+    <el-form-item :label="t('list.values')">
       <el-input
         v-model="rawList"
         type="textarea"
         :rows="8"
-        placeholder="яблоко&#10;банан&#10;вишня"
+        :placeholder="t('list.placeholder')"
       />
     </el-form-item>
-    <el-form-item label="Количество">
+    <el-form-item :label="t('list.count')">
       <el-input-number v-model="count" :min="1" :controls="true" />
     </el-form-item>
     <el-form-item>
-      <el-checkbox v-model="unique">Только уникальные значения</el-checkbox>
+      <el-checkbox v-model="unique">{{ t('list.unique') }}</el-checkbox>
     </el-form-item>
     <el-button type="primary" native-type="submit" size="large">
-      Сгенерировать
+      {{ t('list.generate') }}
     </el-button>
   </el-form>
 </template>
 
 <script>
 import { ElMessage } from 'element-plus'
+import { useI18n } from 'vue-i18n'
 import { generateFromList } from '@/utils/random'
 import { loadFormState, saveFormState } from '@/utils/persistForm'
 
@@ -35,6 +36,10 @@ const DEFAULTS = {
 export default {
   name: 'ListGenerator',
   emits: ['result'],
+  setup() {
+    const { t } = useI18n()
+    return { t }
+  },
   data() {
     return loadFormState(STORAGE_KEY, DEFAULTS)
   },
@@ -61,17 +66,23 @@ export default {
     },
     onGenerate() {
       if (!this.items.length) {
-        ElMessage.error('Список пуст — добавьте хотя бы одно значение')
+        ElMessage.error(this.t('list.errEmpty'))
         return
       }
       if (this.count < 1) {
-        ElMessage.error('Количество должно быть не меньше 1')
+        ElMessage.error(this.t('list.errCount'))
         return
       }
       try {
         this.$emit('result', generateFromList(this.items, this.count, this.unique))
       } catch (err) {
-        ElMessage.error(err.message)
+        const key =
+          err.code === 'LIST_UNIQUE_TOO_LARGE'
+            ? 'list.errUniqueList'
+            : err.code === 'LIST_EMPTY'
+              ? 'list.errEmpty'
+              : 'list.errCount'
+        ElMessage.error(this.t(key))
       }
     }
   }
diff --git a/src/components/generators/RangeGenerator.vue b/src/components/generators/RangeGenerator.vue
index aa3909f..1453c19 100644
--- a/src/components/generators/RangeGenerator.vue
+++ b/src/components/generators/RangeGenerator.vue
@@ -1,25 +1,26 @@
 <template>
   <el-form label-position="top" class="generator-form" @submit.prevent="onGenerate">
-    <el-form-item label="Минимум">
+    <el-form-item :label="t('range.min')">
       <el-input-number v-model="min" :controls="true" />
     </el-form-item>
-    <el-form-item label="Максимум">
+    <el-form-item :label="t('range.max')">
       <el-input-number v-model="max" :controls="true" />
     </el-form-item>
-    <el-form-item label="Количество">
+    <el-form-item :label="t('range.count')">
       <el-input-number v-model="count" :min="1" :controls="true" />
     </el-form-item>
     <el-form-item>
-      <el-checkbox v-model="unique">Только уникальные значения</el-checkbox>
+      <el-checkbox v-model="unique">{{ t('range.unique') }}</el-checkbox>
     </el-form-item>
     <el-button type="primary" native-type="submit" size="large">
-      Сгенерировать
+      {{ t('range.generate') }}
     </el-button>
   </el-form>
 </template>
 
 <script>
 import { ElMessage } from 'element-plus'
+import { useI18n } from 'vue-i18n'
 import { generateRange } from '@/utils/random'
 import { loadFormState, saveFormState } from '@/utils/persistForm'
 
@@ -34,6 +35,10 @@ const DEFAULTS = {
 export default {
   name: 'RangeGenerator',
   emits: ['result'],
+  setup() {
+    const { t } = useI18n()
+    return { t }
+  },
   data() {
     return loadFormState(STORAGE_KEY, DEFAULTS)
   },
@@ -54,17 +59,18 @@ export default {
     },
     onGenerate() {
       if (this.min > this.max) {
-        ElMessage.error('Минимум не может быть больше максимума')
+        ElMessage.error(this.t('range.errMinMax'))
         return
       }
       if (this.count < 1) {
-        ElMessage.error('Количество должно быть не меньше 1')
+        ElMessage.error(this.t('range.errCount'))
         return
       }
       try {
         this.$emit('result', generateRange(this.min, this.max, this.count, this.unique))
       } catch (err) {
-        ElMessage.error(err.message)
+        const key = err.code === 'RANGE_UNIQUE_TOO_LARGE' ? 'range.errUniqueRange' : 'range.errCount'
+        ElMessage.error(this.t(key))
       }
     }
   }
diff --git a/src/config/appConfig.js b/src/config/appConfig.js
index 329597d..e252eef 100644
--- a/src/config/appConfig.js
+++ b/src/config/appConfig.js
@@ -3,6 +3,7 @@ const DEFAULTS = {
   title: 'irandom',
   brandUrl: 'https://git.imiheev.online/admin/irandom',
   logoUrl: '/logo.png',
+  defaultLocale: 'ru',
   colors: {
     primary: '#c9a66b',
     accent: '#e6c566',
@@ -26,6 +27,7 @@ export function getAppConfig() {
     title: runtime.title || DEFAULTS.title,
     brandUrl: runtime.brandUrl || DEFAULTS.brandUrl,
     logoUrl: runtime.logoUrl || DEFAULTS.logoUrl,
+    defaultLocale: runtime.defaultLocale || DEFAULTS.defaultLocale,
     colors
   }
 }
diff --git a/src/i18n/index.js b/src/i18n/index.js
new file mode 100644
index 0000000..7213032
--- /dev/null
+++ b/src/i18n/index.js
@@ -0,0 +1,64 @@
+import { createI18n } from 'vue-i18n'
+import { getAppConfig } from '@/config/appConfig'
+import ru from './locales/ru'
+import en from './locales/en'
+
+export const LOCALE_STORAGE_KEY = 'irandom:locale'
+export const SUPPORTED_LOCALES = ['ru', 'en']
+
+function normalizeLocale(value) {
+  const code = String(value || '')
+    .trim()
+    .toLowerCase()
+    .slice(0, 2)
+  return SUPPORTED_LOCALES.includes(code) ? code : null
+}
+
+export function resolveInitialLocale() {
+  const stored = normalizeLocale(
+    typeof localStorage !== 'undefined' ? localStorage.getItem(LOCALE_STORAGE_KEY) : null
+  )
+  if (stored) {
+    return stored
+  }
+
+  const fromEnv = normalizeLocale(getAppConfig().defaultLocale)
+  return fromEnv || 'ru'
+}
+
+export function persistLocale(locale) {
+  const code = normalizeLocale(locale)
+  if (!code) {
+    return
+  }
+  try {
+    localStorage.setItem(LOCALE_STORAGE_KEY, code)
+  } catch {
+    // ignore
+  }
+}
+
+export function setAppLocale(i18n, locale) {
+  const code = normalizeLocale(locale)
+  if (!code) {
+    return
+  }
+  i18n.global.locale.value = code
+  persistLocale(code)
+  if (typeof document !== 'undefined') {
+    document.documentElement.lang = code
+  }
+}
+
+const i18n = createI18n({
+  legacy: false,
+  locale: resolveInitialLocale(),
+  fallbackLocale: 'ru',
+  messages: { ru, en }
+})
+
+if (typeof document !== 'undefined') {
+  document.documentElement.lang = i18n.global.locale.value
+}
+
+export default i18n
diff --git a/src/i18n/locales/en.js b/src/i18n/locales/en.js
new file mode 100644
index 0000000..cf84bcd
--- /dev/null
+++ b/src/i18n/locales/en.js
@@ -0,0 +1,53 @@
+export default {
+  nav: {
+    range: 'Range',
+    list: 'List',
+    coin: 'Heads / Tails',
+    language: 'Language',
+    collapse: 'Collapse',
+    expand: 'Expand',
+    modes: 'Generation modes'
+  },
+  lang: {
+    ru: 'Русский',
+    en: 'English'
+  },
+  range: {
+    title: 'Numbers from a range',
+    description: 'Generate several random integers within a chosen range.',
+    min: 'Minimum',
+    max: 'Maximum',
+    count: 'Count',
+    unique: 'Unique values only',
+    generate: 'Generate',
+    errMinMax: 'Minimum cannot be greater than maximum',
+    errCount: 'Count must be at least 1',
+    errUniqueRange: 'Unique count cannot exceed the size of the range'
+  },
+  list: {
+    title: 'Values from a list',
+    description: 'Enter a list and pick random items from it.',
+    values: 'List of values (one per line)',
+    placeholder: 'apple\nbanana\ncherry',
+    count: 'Count',
+    unique: 'Unique values only',
+    generate: 'Generate',
+    errEmpty: 'The list is empty — add at least one value',
+    errCount: 'Count must be at least 1',
+    errUniqueList: 'Unique count cannot exceed the list length'
+  },
+  coin: {
+    title: 'Heads / Tails',
+    description: 'Flip a coin once or several times.',
+    flips: 'Number of flips',
+    hint: 'Each flip is either heads or tails.',
+    generate: 'Generate',
+    errCount: 'Count must be at least 1',
+    heads: 'heads',
+    tails: 'tails'
+  },
+  result: {
+    label: 'Result',
+    empty: 'Press “Generate”'
+  }
+}
diff --git a/src/i18n/locales/ru.js b/src/i18n/locales/ru.js
new file mode 100644
index 0000000..39b82b0
--- /dev/null
+++ b/src/i18n/locales/ru.js
@@ -0,0 +1,53 @@
+export default {
+  nav: {
+    range: 'Диапазон',
+    list: 'Список',
+    coin: 'Орёл / решка',
+    language: 'Язык',
+    collapse: 'Свернуть',
+    expand: 'Развернуть',
+    modes: 'Режимы генерации'
+  },
+  lang: {
+    ru: 'Русский',
+    en: 'English'
+  },
+  range: {
+    title: 'Числа из диапазона',
+    description: 'Сгенерируйте несколько случайных чисел в заданном диапазоне.',
+    min: 'Минимум',
+    max: 'Максимум',
+    count: 'Количество',
+    unique: 'Только уникальные значения',
+    generate: 'Сгенерировать',
+    errMinMax: 'Минимум не может быть больше максимума',
+    errCount: 'Количество должно быть не меньше 1',
+    errUniqueRange: 'Количество уникальных значений не может превышать размер диапазона'
+  },
+  list: {
+    title: 'Значения из списка',
+    description: 'Введите список и выберите случайные элементы из него.',
+    values: 'Список значений (по одному на строку)',
+    placeholder: 'яблоко\nбанан\nвишня',
+    count: 'Количество',
+    unique: 'Только уникальные значения',
+    generate: 'Сгенерировать',
+    errEmpty: 'Список пуст — добавьте хотя бы одно значение',
+    errCount: 'Количество должно быть не меньше 1',
+    errUniqueList: 'Количество уникальных значений не может превышать длину списка'
+  },
+  coin: {
+    title: 'Орёл / решка',
+    description: 'Подбросьте монетку один или несколько раз.',
+    flips: 'Количество бросков',
+    hint: 'Каждый бросок даёт «орёл» или «решку».',
+    generate: 'Сгенерировать',
+    errCount: 'Количество должно быть не меньше 1',
+    heads: 'орёл',
+    tails: 'решка'
+  },
+  result: {
+    label: 'Результат',
+    empty: 'Нажмите «Сгенерировать»'
+  }
+}
diff --git a/src/main.js b/src/main.js
index e6b5cce..033fed4 100644
--- a/src/main.js
+++ b/src/main.js
@@ -4,6 +4,7 @@ import 'element-plus/dist/index.css'
 import './styles/theme.css'
 import App from './App.vue'
 import router from './router'
+import i18n from './i18n'
 import { getAppConfig } from './config/appConfig'
 import { applyTheme } from './config/applyTheme'
 
@@ -11,4 +12,4 @@ const appConfig = getAppConfig()
 applyTheme(appConfig)
 document.title = appConfig.title
 
-createApp(App).use(router).use(ElementPlus).mount('#app')
+createApp(App).use(router).use(i18n).use(ElementPlus).mount('#app')
diff --git a/src/router/index.js b/src/router/index.js
index d72b239..2e4361d 100644
--- a/src/router/index.js
+++ b/src/router/index.js
@@ -6,29 +6,17 @@ const routes = [
   {
     path: '/range',
     name: 'range',
-    component: GeneratorView,
-    meta: {
-      title: 'Числа из диапазона',
-      description: 'Сгенерируйте несколько случайных чисел в заданном диапазоне.'
-    }
+    component: GeneratorView
   },
   {
     path: '/list',
     name: 'list',
-    component: GeneratorView,
-    meta: {
-      title: 'Значения из списка',
-      description: 'Введите список и выберите случайные элементы из него.'
-    }
+    component: GeneratorView
   },
   {
     path: '/coin',
     name: 'coin',
-    component: GeneratorView,
-    meta: {
-      title: 'Орёл / решка',
-      description: 'Подбросьте монетку один или несколько раз.'
-    }
+    component: GeneratorView
   },
   { path: '/:pathMatch(.*)*', redirect: '/range' }
 ]
diff --git a/src/utils/random.js b/src/utils/random.js
index 5b29ade..97d573d 100644
--- a/src/utils/random.js
+++ b/src/utils/random.js
@@ -14,6 +14,12 @@ export function generateNumber(min, max) {
   return randomInt(min, max)
 }
 
+function codedError(code) {
+  const err = new Error(code)
+  err.code = code
+  return err
+}
+
 /**
  * N random integers in [min, max].
  * When unique is true, values are distinct (count cannot exceed range size).
@@ -25,7 +31,7 @@ export function generateRange(min, max, count, unique = false) {
 
   if (unique) {
     if (count > span) {
-      throw new Error('Количество уникальных значений не может превышать размер диапазона')
+      throw codedError('RANGE_UNIQUE_TOO_LARGE')
     }
     const pool = Array.from({ length: span }, (_, i) => lo + i)
     for (let i = pool.length - 1; i > 0; i -= 1) {
@@ -44,12 +50,12 @@ export function generateRange(min, max, count, unique = false) {
  */
 export function generateFromList(items, count, unique = false) {
   if (!items.length) {
-    throw new Error('Список пуст')
+    throw codedError('LIST_EMPTY')
   }
 
   if (unique) {
     if (count > items.length) {
-      throw new Error('Количество уникальных значений не может превышать длину списка')
+      throw codedError('LIST_UNIQUE_TOO_LARGE')
     }
     const pool = [...items]
     for (let i = pool.length - 1; i > 0; i -= 1) {
@@ -63,8 +69,8 @@ export function generateFromList(items, count, unique = false) {
 }
 
 /**
- * Coin flips: returns array of 'орёл' | 'решка'.
+ * Coin flips: returns array of 'heads' | 'tails'.
  */
 export function flipCoin(count = 1) {
-  return Array.from({ length: count }, () => (Math.random() < 0.5 ? 'орёл' : 'решка'))
+  return Array.from({ length: count }, () => (Math.random() < 0.5 ? 'heads' : 'tails'))
 }
diff --git a/src/views/GeneratorView.vue b/src/views/GeneratorView.vue
index f0a9ff0..c05170f 100644
--- a/src/views/GeneratorView.vue
+++ b/src/views/GeneratorView.vue
@@ -9,6 +9,7 @@
 </template>
 
 <script>
+import { useI18n } from 'vue-i18n'
 import ResultDisplay from '@/components/ResultDisplay.vue'
 import RangeGenerator from '@/components/generators/RangeGenerator.vue'
 import ListGenerator from '@/components/generators/ListGenerator.vue'
@@ -20,6 +21,12 @@ const GENERATORS = {
   coin: CoinGenerator
 }
 
+const META_KEYS = {
+  range: { title: 'range.title', description: 'range.description' },
+  list: { title: 'list.title', description: 'list.description' },
+  coin: { title: 'coin.title', description: 'coin.description' }
+}
+
 export default {
   name: 'GeneratorView',
   components: {
@@ -28,6 +35,10 @@ export default {
     ListGenerator,
     CoinGenerator
   },
+  setup() {
+    const { t } = useI18n()
+    return { t }
+  },
   data() {
     return {
       result: null
@@ -35,10 +46,12 @@ export default {
   },
   computed: {
     title() {
-      return this.$route.meta.title ?? ''
+      const keys = META_KEYS[this.$route.name]
+      return keys ? this.t(keys.title) : ''
     },
     description() {
-      return this.$route.meta.description ?? ''
+      const keys = META_KEYS[this.$route.name]
+      return keys ? this.t(keys.description) : ''
     },
     generatorComponent() {
       return GENERATORS[this.$route.name] ?? RangeGenerator