diff --git a/frontend/src/App.vue b/frontend/src/App.vue
index ee2e055..9daa55c 100644
--- a/frontend/src/App.vue
+++ b/frontend/src/App.vue
@@ -46,7 +46,13 @@ import SpringboardView from '@/views/SpringboardView.vue'
 
 type AppMessage = {
   type?: string
-  data?: MailEventData | MarketplaceEventData | PhoneCall | PhoneNotificationInput | PhoneOpenPayload
+  data?:
+    | CalendarReminderData
+    | MailEventData
+    | MarketplaceEventData
+    | PhoneCall
+    | PhoneNotificationInput
+    | PhoneOpenPayload
 }
 
 type SimPickerPayload = {
@@ -73,6 +79,15 @@ type MarketplaceEventData = {
   title?: string
 }
 
+type CalendarReminderData = {
+  device?: PhoneNotificationDevicePayload
+  eventId?: string
+  eventTitle?: string
+  startsAt?: number
+  text?: string
+  title?: string
+}
+
 const REFERENCE_VIEWPORT_WIDTH = 1920
 const REFERENCE_VIEWPORT_HEIGHT = 1080
 const PHONE_BASE_SCALE = 0.69
@@ -195,6 +210,30 @@ function onMessage(event: MessageEvent<AppMessage>): void {
     }
     notifications.show(notification)
     void marketplace.loadCounts()
+  } else if (event.data?.type === 'calendar:reminder' && event.data.data) {
+    const data = event.data.data as CalendarReminderData
+    const startsAt = Number(data.startsAt) || Date.now()
+    const notification: PhoneNotificationInput = {
+      appId: 'calendar',
+      subtitle: new Intl.DateTimeFormat(phone.lang, {
+        hour: '2-digit',
+        minute: '2-digit',
+      }).format(startsAt),
+      text:
+        data.text ??
+        phone.t('Apps.calendar.reminderNotification', {
+          title: data.eventTitle ?? '',
+        }),
+      title: data.title ?? phone.t('Apps.calendar.name'),
+    }
+    if (data.device && (!phone.isOpen || data.device.imei !== phone.device?.imei)) {
+      notification.device = {
+        imei: data.device.imei,
+        name: data.device.name,
+        preferences: parsePhonePreferences(data.device.settings ?? null),
+      }
+    }
+    notifications.show(notification)
   } else if (event.data?.type === 'contacts:changed') {
     void calls.loadContacts()
   } else if (event.data?.type === 'calls:changed') {
diff --git a/frontend/src/assets/img/app-icons/calendar.svg b/frontend/src/assets/img/app-icons/calendar.svg
new file mode 100644
index 0000000..6c34aa8
--- /dev/null
+++ b/frontend/src/assets/img/app-icons/calendar.svg
@@ -0,0 +1,26 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 256 256" role="img" aria-label="Calendar">
+  <defs>
+    <linearGradient id="bg" x1="32" y1="20" x2="224" y2="236" gradientUnits="userSpaceOnUse">
+      <stop stop-color="#ff765f"/>
+      <stop offset="1" stop-color="#e93147"/>
+    </linearGradient>
+    <filter id="shadow" x="-20%" y="-20%" width="140%" height="150%">
+      <feDropShadow dx="0" dy="10" stdDeviation="10" flood-color="#8c1021" flood-opacity=".32"/>
+    </filter>
+  </defs>
+  <rect width="256" height="256" rx="58" fill="url(#bg)"/>
+  <g filter="url(#shadow)">
+    <rect x="42" y="50" width="172" height="164" rx="28" fill="#fff"/>
+    <path d="M42 78c0-15.5 12.5-28 28-28h116c15.5 0 28 12.5 28 28v26H42V78Z" fill="#f8e9eb"/>
+    <rect x="77" y="36" width="14" height="42" rx="7" fill="#fff"/>
+    <rect x="165" y="36" width="14" height="42" rx="7" fill="#fff"/>
+    <g fill="#d5d8df">
+      <rect x="67" y="124" width="26" height="21" rx="7"/><rect x="104" y="124" width="26" height="21" rx="7"/><rect x="141" y="124" width="26" height="21" rx="7"/>
+      <rect x="67" y="157" width="26" height="21" rx="7"/><rect x="141" y="157" width="26" height="21" rx="7"/>
+    </g>
+    <rect x="101" y="153" width="32" height="29" rx="9" fill="#ff4259"/>
+    <path d="m109 167 7 7 11-14" fill="none" stroke="#fff" stroke-width="5" stroke-linecap="round" stroke-linejoin="round"/>
+  </g>
+  <circle cx="201" cy="198" r="27" fill="#272b36" stroke="#fff" stroke-width="6"/>
+  <path d="M201 183v16l10 7" fill="none" stroke="#fff" stroke-width="6" stroke-linecap="round" stroke-linejoin="round"/>
+</svg>
diff --git a/frontend/src/config/apps.test.ts b/frontend/src/config/apps.test.ts
index 5b5b963..a5fd6bd 100644
--- a/frontend/src/config/apps.test.ts
+++ b/frontend/src/config/apps.test.ts
@@ -10,9 +10,11 @@ describe('app registry', () => {
         (app) => app.route === null || app.route === `/apps/${app.id}`,
       ),
     ).toBe(true)
-    expect(PHONE_APPS.every((app) => app.iconImage.endsWith('.webp'))).toBe(
-      true,
-    )
+    expect(
+      PHONE_APPS.every(
+        (app) => typeof app.iconImage === 'string' && app.iconImage.length > 0,
+      ),
+    ).toBe(true)
     expect(PHONE_APPS.find((app) => app.id === 'phone')).toMatchObject({
       dockOrder: 0,
       labelKey: 'Apps.phone.name',
@@ -28,6 +30,11 @@ describe('app registry', () => {
       labelKey: 'Apps.weather.name',
       route: '/apps/weather',
     })
+    expect(PHONE_APPS.find((app) => app.id === 'calendar')).toMatchObject({
+      gridOrder: 20,
+      labelKey: 'Apps.calendar.name',
+      route: '/apps/calendar',
+    })
     expect(PHONE_APPS.find((app) => app.id === 'snake')).toMatchObject({
       dockOrder: null,
       gridOrder: 11,
diff --git a/frontend/src/config/apps.ts b/frontend/src/config/apps.ts
index b1af4d2..9377063 100644
--- a/frontend/src/config/apps.ts
+++ b/frontend/src/config/apps.ts
@@ -3,6 +3,7 @@ import {
   Bomb,
   Blocks,
   Camera,
+  CalendarDays,
   Clock3,
   Gamepad2,
   Grid2X2,
@@ -26,6 +27,7 @@ import appStoreIcon from '@/assets/img/app-icons/apps.webp'
 import calculatorIcon from '@/assets/img/app-icons/calculator.webp'
 import cameraIcon from '@/assets/img/app-icons/camera.webp'
 import clockIcon from '@/assets/img/app-icons/clock.webp'
+import calendarIcon from '@/assets/img/app-icons/calendar.svg'
 import mailIcon from '@/assets/img/app-icons/mail.webp'
 import mapIcon from '@/assets/img/app-icons/map.webp'
 import notesIcon from '@/assets/img/app-icons/notes.webp'
@@ -49,6 +51,19 @@ import type {
 } from '@/types/apps'
 
 export const PHONE_APPS: PhoneAppDefinition[] = [
+  {
+    component: markRaw(
+      defineAsyncComponent(() => import('@/views/apps/CalendarApp.vue')),
+    ),
+    dockOrder: null,
+    gridOrder: 20,
+    icon: markRaw(CalendarDays),
+    iconClass: 'app-icon--calendar',
+    iconImage: calendarIcon,
+    id: 'calendar',
+    labelKey: 'Apps.calendar.name',
+    route: '/apps/calendar',
+  },
   {
     component: markRaw(
       defineAsyncComponent(() => import('@/views/apps/LocalPagesApp.vue')),
diff --git a/frontend/src/stores/calendar.test.ts b/frontend/src/stores/calendar.test.ts
new file mode 100644
index 0000000..f46de96
--- /dev/null
+++ b/frontend/src/stores/calendar.test.ts
@@ -0,0 +1,61 @@
+import { createPinia, setActivePinia } from 'pinia'
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+
+import { useCalendarStore } from '@/stores/calendar'
+import { nuiCall } from '@/utils/nui'
+
+vi.mock('@/utils/nui', () => ({ nuiCall: vi.fn() }))
+const mockNuiCall = vi.mocked(nuiCall)
+
+describe('calendar store', () => {
+  beforeEach(() => {
+    setActivePinia(createPinia())
+    mockNuiCall.mockReset()
+  })
+
+  it('loads a bounded calendar range', async () => {
+    mockNuiCall.mockResolvedValueOnce({ data: [], success: true })
+    const calendar = useCalendarStore()
+
+    expect(await calendar.load(1_000_000, 2_000_000)).toBe(true)
+    expect(mockNuiCall).toHaveBeenCalledWith('calendar:list', {
+      endsAt: 2000,
+      startsAt: 1000,
+    })
+  })
+
+  it('sends server timestamps and revisions when updating', async () => {
+    mockNuiCall.mockResolvedValueOnce({ success: true })
+    const calendar = useCalendarStore()
+
+    await calendar.update(
+      {
+        endsAt: 0,
+        id: 'event-id',
+        note: '',
+        remindedAt: null,
+        reminderMinutes: null,
+        revision: 4,
+        startsAt: 0,
+        title: '',
+      },
+      {
+        endsAt: 2_000_000,
+        note: 'Bring documents',
+        reminderMinutes: 60,
+        startsAt: 1_000_000,
+        title: 'Meeting',
+      },
+    )
+
+    expect(mockNuiCall).toHaveBeenCalledWith('calendar:update', {
+      endsAt: 2000,
+      id: 'event-id',
+      note: 'Bring documents',
+      reminderMinutes: 60,
+      revision: 4,
+      startsAt: 1000,
+      title: 'Meeting',
+    })
+  })
+})
diff --git a/frontend/src/stores/calendar.ts b/frontend/src/stores/calendar.ts
new file mode 100644
index 0000000..682b058
--- /dev/null
+++ b/frontend/src/stores/calendar.ts
@@ -0,0 +1,63 @@
+import { defineStore } from 'pinia'
+
+import type { CalendarEvent, CalendarEventDraft } from '@/types/calendar'
+import { nuiCall } from '@/utils/nui'
+
+function toServerDraft(draft: CalendarEventDraft): Record<string, unknown> {
+  return {
+    endsAt: Math.floor(draft.endsAt / 1000),
+    note: draft.note,
+    reminderMinutes: draft.reminderMinutes,
+    startsAt: Math.floor(draft.startsAt / 1000),
+    title: draft.title,
+  }
+}
+
+export const useCalendarStore = defineStore('calendar', {
+  state: () => ({
+    error: '' as string,
+    events: [] as CalendarEvent[],
+    loading: false,
+  }),
+  actions: {
+    async create(draft: CalendarEventDraft): Promise<boolean> {
+      const response = await nuiCall<{ id: string }>(
+        'calendar:create',
+        toServerDraft(draft),
+      )
+      this.error = response.success ? '' : (response.error ?? 'default')
+      return response.success
+    },
+    async deleteEvent(id: string): Promise<boolean> {
+      const response = await nuiCall('calendar:delete', { id })
+      this.error = response.success ? '' : (response.error ?? 'default')
+      if (response.success) {
+        this.events = this.events.filter((event) => event.id !== id)
+      }
+      return response.success
+    },
+    async load(startsAt: number, endsAt: number): Promise<boolean> {
+      this.loading = true
+      const response = await nuiCall<CalendarEvent[]>('calendar:list', {
+        endsAt: Math.floor(endsAt / 1000),
+        startsAt: Math.floor(startsAt / 1000),
+      })
+      this.loading = false
+      this.error = response.success ? '' : (response.error ?? 'default')
+      if (response.success) this.events = response.data ?? []
+      return response.success
+    },
+    async update(
+      event: CalendarEvent,
+      draft: CalendarEventDraft,
+    ): Promise<boolean> {
+      const response = await nuiCall('calendar:update', {
+        ...toServerDraft(draft),
+        id: event.id,
+        revision: event.revision,
+      })
+      this.error = response.success ? '' : (response.error ?? 'default')
+      return response.success
+    },
+  },
+})
diff --git a/frontend/src/stores/phone.ts b/frontend/src/stores/phone.ts
index 5d74bad..753f768 100644
--- a/frontend/src/stores/phone.ts
+++ b/frontend/src/stores/phone.ts
@@ -522,6 +522,47 @@ const defaultLocales: LocaleTree = {
         upload_timeout: 'The media upload timed out.',
       },
     },
+    calendar: {
+      name: 'Calendar',
+      eyebrow: 'Your time. Clearly planned.',
+      schedule: 'Schedule',
+      event: 'Event',
+      appointment: 'Appointment',
+      newEvent: 'New event',
+      editEvent: 'Edit event',
+      deleteEvent: 'Delete event',
+      details: 'Event details',
+      title: 'Title',
+      titlePlaceholder: 'What is planned?',
+      date: 'Date',
+      starts: 'Starts',
+      ends: 'Ends',
+      reminder: 'Reminder',
+      note: 'Note',
+      notePlaceholder: 'Add details, an address or anything to remember...',
+      noEvents: 'Nothing planned',
+      noEventsBody: 'This day is still free. Add an event whenever you are ready.',
+      signInTitle: 'Your iFruit calendar',
+      signInBody: 'Sign in to iFruit in Settings to sync appointments and receive reminders.',
+      reminderNotification: 'Upcoming: {title}',
+      reminders: {
+        none: 'No reminder',
+        atStart: 'At start time',
+        tenMinutes: '10 minutes before',
+        thirtyMinutes: '30 minutes before',
+        oneHour: '1 hour before',
+        oneDay: '1 day before',
+      },
+      errors: {
+        invalid_event: 'Enter a title and make sure the end is after the start.',
+        invalid_range: 'This calendar period is invalid.',
+        conflict: 'This event changed on another phone. Open it again.',
+        rate_limited: 'Too many changes. Try again shortly.',
+        not_authenticated: 'Sign in to your iFruit account first.',
+        request_failed: 'Calendar is temporarily unavailable.',
+        default: 'The calendar request failed.',
+      },
+    },
     clock: {
       name: 'Clock',
       lap: 'Lap',
diff --git a/frontend/src/types/apps.ts b/frontend/src/types/apps.ts
index 4058056..fe27ca5 100644
--- a/frontend/src/types/apps.ts
+++ b/frontend/src/types/apps.ts
@@ -5,6 +5,7 @@ export type PhoneAppId =
   | 'calculator'
   | 'camera'
   | 'clock'
+  | 'calendar'
   | 'weather'
   | 'mail'
   | 'map'
diff --git a/frontend/src/types/calendar.ts b/frontend/src/types/calendar.ts
new file mode 100644
index 0000000..957b259
--- /dev/null
+++ b/frontend/src/types/calendar.ts
@@ -0,0 +1,18 @@
+export type CalendarEvent = {
+  endsAt: number
+  id: string
+  note: string
+  remindedAt: number | null
+  reminderMinutes: number | null
+  revision: number
+  startsAt: number
+  title: string
+}
+
+export type CalendarEventDraft = {
+  endsAt: number
+  note: string
+  reminderMinutes: number | null
+  startsAt: number
+  title: string
+}
diff --git a/frontend/src/utils/preferences.ts b/frontend/src/utils/preferences.ts
index 8194514..b68589f 100644
--- a/frontend/src/utils/preferences.ts
+++ b/frontend/src/utils/preferences.ts
@@ -61,6 +61,7 @@ const DEFAULT_APP_NOTIFICATIONS: Record<
   'local-pages': { enabled: true, sounds: true },
   camera: { enabled: true, sounds: true },
   clock: { enabled: true, sounds: true },
+  calendar: { enabled: true, sounds: true },
   weather: { enabled: true, sounds: true },
   mail: { enabled: true, sounds: true },
   map: { enabled: true, sounds: true },
diff --git a/frontend/src/views/apps/CalendarApp.vue b/frontend/src/views/apps/CalendarApp.vue
new file mode 100644
index 0000000..7688abc
--- /dev/null
+++ b/frontend/src/views/apps/CalendarApp.vue
@@ -0,0 +1,383 @@
+<script setup lang="ts">
+import {
+  Bell,
+  CalendarDays,
+  Check,
+  ChevronLeft,
+  ChevronRight,
+  Clock3,
+  FileText,
+  Pencil,
+  Plus,
+  Trash2,
+  UserRound,
+  X,
+} from 'lucide-vue-next'
+import { computed, onMounted, reactive, ref } from 'vue'
+import { useRouter } from 'vue-router'
+
+import { useAccountStore } from '@/stores/account'
+import { useCalendarStore } from '@/stores/calendar'
+import { usePhoneStore } from '@/stores/phone'
+import type { CalendarEvent, CalendarEventDraft } from '@/types/calendar'
+
+type CalendarScreen = 'main' | 'detail' | 'form'
+
+const reminderOptions = [null, 0, 10, 30, 60, 1440] as const
+const router = useRouter()
+const phone = usePhoneStore()
+const account = useAccountStore()
+const calendar = useCalendarStore()
+const today = new Date()
+const visibleMonth = ref(new Date(today.getFullYear(), today.getMonth(), 1))
+const selectedDate = ref(dateKey(today))
+const selectedEvent = ref<CalendarEvent | null>(null)
+const editingEvent = ref<CalendarEvent | null>(null)
+const screen = ref<CalendarScreen>('main')
+const reminderOpen = ref(false)
+const saving = ref(false)
+const formError = ref('')
+const draft = reactive({
+  date: selectedDate.value,
+  endTime: '10:00',
+  note: '',
+  reminderMinutes: 60 as number | null,
+  startTime: '09:00',
+  title: '',
+})
+
+function dateKey(value: Date | number): string {
+  const date = new Date(value)
+  const year = date.getFullYear()
+  const month = String(date.getMonth() + 1).padStart(2, '0')
+  const day = String(date.getDate()).padStart(2, '0')
+  return `${year}-${month}-${day}`
+}
+
+function timeValue(value: number): string {
+  const date = new Date(value)
+  return `${String(date.getHours()).padStart(2, '0')}:${String(date.getMinutes()).padStart(2, '0')}`
+}
+
+function combineDateAndTime(date: string, time: string): number {
+  const [year, month, day] = date.split('-').map(Number)
+  const [hour, minute] = time.split(':').map(Number)
+  return new Date(year, month - 1, day, hour, minute).getTime()
+}
+
+function addDays(value: Date, amount: number): Date {
+  return new Date(value.getFullYear(), value.getMonth(), value.getDate() + amount)
+}
+
+function calendarGridStart(month: Date): Date {
+  const first = new Date(month.getFullYear(), month.getMonth(), 1)
+  const mondayOffset = (first.getDay() + 6) % 7
+  return addDays(first, -mondayOffset)
+}
+
+const isAuthenticated = computed(() => account.email !== '')
+const monthLabel = computed(() =>
+  new Intl.DateTimeFormat(phone.lang, {
+    month: 'long',
+    year: 'numeric',
+  }).format(visibleMonth.value),
+)
+const weekdayLabels = computed(() => {
+  const monday = new Date(2026, 0, 5)
+  return Array.from({ length: 7 }, (_, index) =>
+    new Intl.DateTimeFormat(phone.lang, { weekday: 'narrow' }).format(
+      addDays(monday, index),
+    ),
+  )
+})
+const monthDays = computed(() => {
+  const start = calendarGridStart(visibleMonth.value)
+  return Array.from({ length: 42 }, (_, index) => addDays(start, index))
+})
+const selectedEvents = computed(() =>
+  calendar.events
+    .filter((event) => dateKey(event.startsAt) === selectedDate.value)
+    .sort((left, right) => left.startsAt - right.startsAt),
+)
+const selectedDateLabel = computed(() =>
+  new Intl.DateTimeFormat(phone.lang, {
+    day: 'numeric',
+    month: 'long',
+    weekday: 'long',
+  }).format(new Date(`${selectedDate.value}T12:00:00`)),
+)
+
+function hasEvents(day: Date): boolean {
+  const key = dateKey(day)
+  return calendar.events.some((event) => dateKey(event.startsAt) === key)
+}
+
+function formatTime(value: number): string {
+  return new Intl.DateTimeFormat(phone.lang, {
+    hour: '2-digit',
+    minute: '2-digit',
+  }).format(value)
+}
+
+function formatLongDate(value: number): string {
+  return new Intl.DateTimeFormat(phone.lang, {
+    day: 'numeric',
+    month: 'long',
+    weekday: 'long',
+    year: 'numeric',
+  }).format(value)
+}
+
+function reminderLabel(minutes: number | null): string {
+  if (minutes === null) return phone.t('Apps.calendar.reminders.none')
+  if (minutes === 0) return phone.t('Apps.calendar.reminders.atStart')
+  if (minutes === 10) return phone.t('Apps.calendar.reminders.tenMinutes')
+  if (minutes === 30) return phone.t('Apps.calendar.reminders.thirtyMinutes')
+  if (minutes === 60) return phone.t('Apps.calendar.reminders.oneHour')
+  return phone.t('Apps.calendar.reminders.oneDay')
+}
+
+async function loadMonth(): Promise<void> {
+  if (!isAuthenticated.value) {
+    calendar.events = []
+    return
+  }
+  const start = calendarGridStart(visibleMonth.value)
+  await calendar.load(start.getTime(), addDays(start, 42).getTime())
+}
+
+async function moveMonth(amount: number): Promise<void> {
+  visibleMonth.value = new Date(
+    visibleMonth.value.getFullYear(),
+    visibleMonth.value.getMonth() + amount,
+    1,
+  )
+  selectedDate.value = dateKey(visibleMonth.value)
+  await loadMonth()
+}
+
+function selectDay(day: Date): void {
+  selectedDate.value = dateKey(day)
+  if (day.getMonth() !== visibleMonth.value.getMonth()) {
+    visibleMonth.value = new Date(day.getFullYear(), day.getMonth(), 1)
+    void loadMonth()
+  }
+}
+
+function resetDraft(event?: CalendarEvent): void {
+  editingEvent.value = event ?? null
+  draft.title = event?.title ?? ''
+  draft.note = event?.note ?? ''
+  draft.date = event ? dateKey(event.startsAt) : selectedDate.value
+  draft.startTime = event ? timeValue(event.startsAt) : '09:00'
+  draft.endTime = event ? timeValue(event.endsAt) : '10:00'
+  draft.reminderMinutes = event?.reminderMinutes ?? 60
+  reminderOpen.value = false
+  formError.value = ''
+}
+
+function openCreate(): void {
+  resetDraft()
+  screen.value = 'form'
+}
+
+function openDetail(event: CalendarEvent): void {
+  selectedEvent.value = event
+  screen.value = 'detail'
+}
+
+function openEdit(): void {
+  if (!selectedEvent.value) return
+  resetDraft(selectedEvent.value)
+  screen.value = 'form'
+}
+
+async function saveEvent(): Promise<void> {
+  const startsAt = combineDateAndTime(draft.date, draft.startTime)
+  const endsAt = combineDateAndTime(draft.date, draft.endTime)
+  if (!draft.title.trim() || endsAt <= startsAt) {
+    formError.value = phone.t('Apps.calendar.errors.invalid_event')
+    return
+  }
+  const payload: CalendarEventDraft = {
+    endsAt,
+    note: draft.note.trim(),
+    reminderMinutes: draft.reminderMinutes,
+    startsAt,
+    title: draft.title.trim(),
+  }
+  saving.value = true
+  const success = editingEvent.value
+    ? await calendar.update(editingEvent.value, payload)
+    : await calendar.create(payload)
+  saving.value = false
+  if (!success) {
+    formError.value = phone.t(
+      `Apps.calendar.errors.${calendar.error || 'default'}`,
+    )
+    return
+  }
+  selectedDate.value = draft.date
+  visibleMonth.value = new Date(startsAt)
+  visibleMonth.value = new Date(
+    visibleMonth.value.getFullYear(),
+    visibleMonth.value.getMonth(),
+    1,
+  )
+  await loadMonth()
+  screen.value = 'main'
+}
+
+async function deleteEvent(): Promise<void> {
+  if (!selectedEvent.value || !(await calendar.deleteEvent(selectedEvent.value.id))) {
+    return
+  }
+  selectedEvent.value = null
+  screen.value = 'main'
+}
+
+onMounted(loadMonth)
+</script>
+
+<template>
+  <main class="calendar" :class="{ 'calendar--light': !phone.isDarkMode }">
+    <template v-if="screen === 'main'">
+      <header class="calendar__header">
+        <button :aria-label="phone.t('Common.home')" type="button" @click="router.push('/')">
+          <ChevronLeft :size="19" />
+        </button>
+        <div>
+          <span>{{ phone.t('Apps.calendar.eyebrow') }}</span>
+          <h1>{{ phone.t('Apps.calendar.name') }}</h1>
+        </div>
+        <button v-if="isAuthenticated" :aria-label="phone.t('Apps.calendar.newEvent')" type="button" @click="openCreate">
+          <Plus :size="20" />
+        </button>
+        <span v-else />
+      </header>
+
+      <section v-if="!isAuthenticated" class="calendar__auth">
+        <UserRound :size="43" />
+        <h2>{{ phone.t('Apps.calendar.signInTitle') }}</h2>
+        <p>{{ phone.t('Apps.calendar.signInBody') }}</p>
+      </section>
+
+      <div v-else class="calendar__content">
+        <section class="calendar__month">
+          <div class="calendar__month-nav">
+            <button type="button" @click="moveMonth(-1)"><ChevronLeft :size="18" /></button>
+            <strong>{{ monthLabel }}</strong>
+            <button type="button" @click="moveMonth(1)"><ChevronRight :size="18" /></button>
+          </div>
+          <div class="calendar__weekdays">
+            <span v-for="weekday in weekdayLabels" :key="weekday">{{ weekday }}</span>
+          </div>
+          <div class="calendar__grid">
+            <button
+              v-for="day in monthDays"
+              :key="dateKey(day)"
+              type="button"
+              :class="{
+                selected: dateKey(day) === selectedDate,
+                today: dateKey(day) === dateKey(today),
+                outside: day.getMonth() !== visibleMonth.getMonth(),
+              }"
+              @click="selectDay(day)"
+            >
+              <span>{{ day.getDate() }}</span>
+              <i v-if="hasEvents(day)" />
+            </button>
+          </div>
+        </section>
+
+        <section class="calendar__agenda">
+          <div class="calendar__agenda-title">
+            <div>
+              <small>{{ phone.t('Apps.calendar.schedule') }}</small>
+              <h2>{{ selectedDateLabel }}</h2>
+            </div>
+            <span>{{ selectedEvents.length }}</span>
+          </div>
+          <div v-if="calendar.loading" class="calendar__empty">{{ phone.t('Common.loading') }}</div>
+          <div v-else-if="!selectedEvents.length" class="calendar__empty">
+            <CalendarDays :size="28" />
+            <strong>{{ phone.t('Apps.calendar.noEvents') }}</strong>
+            <span>{{ phone.t('Apps.calendar.noEventsBody') }}</span>
+            <button type="button" @click="openCreate"><Plus :size="15" /> {{ phone.t('Apps.calendar.newEvent') }}</button>
+          </div>
+          <button
+            v-for="event in selectedEvents"
+            v-else
+            :key="event.id"
+            class="calendar__event"
+            type="button"
+            @click="openDetail(event)"
+          >
+            <span><b>{{ formatTime(event.startsAt) }}</b><small>{{ formatTime(event.endsAt) }}</small></span>
+            <i />
+            <div><strong>{{ event.title }}</strong><small>{{ event.note || reminderLabel(event.reminderMinutes) }}</small></div>
+            <ChevronRight :size="16" />
+          </button>
+        </section>
+      </div>
+    </template>
+
+    <section v-else-if="screen === 'detail' && selectedEvent" class="calendar__detail">
+      <header>
+        <button type="button" @click="screen = 'main'"><ChevronLeft :size="19" /></button>
+        <strong>{{ phone.t('Apps.calendar.event') }}</strong>
+        <button type="button" @click="openEdit"><Pencil :size="17" /></button>
+      </header>
+      <article>
+        <span class="calendar__detail-icon"><CalendarDays :size="28" /></span>
+        <small>{{ phone.t('Apps.calendar.appointment') }}</small>
+        <h1>{{ selectedEvent.title }}</h1>
+        <div class="calendar__detail-row">
+          <Clock3 :size="18" />
+          <span><small>{{ formatLongDate(selectedEvent.startsAt) }}</small><strong>{{ formatTime(selectedEvent.startsAt) }} – {{ formatTime(selectedEvent.endsAt) }}</strong></span>
+        </div>
+        <div class="calendar__detail-row">
+          <Bell :size="18" />
+          <span><small>{{ phone.t('Apps.calendar.reminder') }}</small><strong>{{ reminderLabel(selectedEvent.reminderMinutes) }}</strong></span>
+        </div>
+        <div v-if="selectedEvent.note" class="calendar__note">
+          <FileText :size="18" />
+          <p>{{ selectedEvent.note }}</p>
+        </div>
+        <button class="calendar__delete" type="button" @click="deleteEvent"><Trash2 :size="16" /> {{ phone.t('Apps.calendar.deleteEvent') }}</button>
+      </article>
+    </section>
+
+    <section v-else class="calendar__form">
+      <header>
+        <button type="button" @click="screen = editingEvent ? 'detail' : 'main'"><X :size="19" /></button>
+        <div><small>{{ editingEvent ? phone.t('Apps.calendar.editEvent') : phone.t('Apps.calendar.newEvent') }}</small><strong>{{ phone.t('Apps.calendar.details') }}</strong></div>
+        <button :disabled="saving" type="button" @click="saveEvent"><Check :size="18" /></button>
+      </header>
+      <form @submit.prevent="saveEvent">
+        <label>{{ phone.t('Apps.calendar.title') }}<input v-model="draft.title" maxlength="120" :placeholder="phone.t('Apps.calendar.titlePlaceholder')" /></label>
+        <label>{{ phone.t('Apps.calendar.date') }}<input v-model="draft.date" type="date" /></label>
+        <div class="calendar__time-row">
+          <label>{{ phone.t('Apps.calendar.starts') }}<input v-model="draft.startTime" type="time" /></label>
+          <label>{{ phone.t('Apps.calendar.ends') }}<input v-model="draft.endTime" type="time" /></label>
+        </div>
+        <label>{{ phone.t('Apps.calendar.reminder') }}</label>
+        <div class="calendar__select">
+          <button type="button" @click="reminderOpen = !reminderOpen"><Bell :size="16" /><span>{{ reminderLabel(draft.reminderMinutes) }}</span><ChevronRight :size="16" :class="{ open: reminderOpen }" /></button>
+          <div v-if="reminderOpen">
+            <button v-for="option in reminderOptions" :key="String(option)" type="button" :class="{ active: draft.reminderMinutes === option }" @click="draft.reminderMinutes = option; reminderOpen = false">
+              {{ reminderLabel(option) }}<Check v-if="draft.reminderMinutes === option" :size="14" />
+            </button>
+          </div>
+        </div>
+        <label>{{ phone.t('Apps.calendar.note') }}<textarea v-model="draft.note" maxlength="2000" :placeholder="phone.t('Apps.calendar.notePlaceholder')" /></label>
+        <p v-if="formError" class="calendar__error">{{ formError }}</p>
+        <button class="calendar__save" :disabled="saving" type="submit">{{ saving ? phone.t('Common.loading') : phone.t('Common.save') }}</button>
+      </form>
+    </section>
+  </main>
+</template>
+
+<style scoped>
+.calendar{--accent:#ff4d5f;--panel:#20242c;--muted:#9da4af;position:absolute;inset:0;padding:47px 0 24px;overflow:hidden;background:#11151b;color:#f8f8f6;font-family:Inter,system-ui,sans-serif}.calendar--light{--panel:#f0f1f4;--muted:#747984;background:#fbfbfc;color:#191b20}.calendar button,.calendar input,.calendar textarea{font:inherit;color:inherit}.calendar button{border:0}.calendar__header{height:65px;padding:7px 14px;display:grid;grid-template-columns:36px 1fr 36px;align-items:center}.calendar__header>button,.calendar__detail>header button,.calendar__form>header>button{width:34px;height:34px;padding:0;border-radius:11px;display:grid;place-items:center;background:var(--panel)}.calendar__header>div{text-align:center}.calendar__header span,.calendar__form header small{display:block;color:var(--accent);font-size:8px;font-weight:900;letter-spacing:.1em;text-transform:uppercase}.calendar__header h1{margin:1px 0 0;font-size:23px;line-height:1}.calendar__content{height:calc(100% - 65px);padding:0 13px 19px;overflow-y:auto;scrollbar-width:none}.calendar__month{padding:11px 10px 9px;border-radius:17px;background:var(--panel);box-shadow:0 8px 24px #0002}.calendar__month-nav{height:31px;display:grid;grid-template-columns:32px 1fr 32px;align-items:center;text-align:center}.calendar__month-nav button{height:29px;padding:0;border-radius:9px;display:grid;place-items:center;background:#ffffff09}.calendar--light .calendar__month-nav button{background:#00000008}.calendar__month-nav strong{font-size:14px;text-transform:capitalize}.calendar__weekdays,.calendar__grid{display:grid;grid-template-columns:repeat(7,1fr)}.calendar__weekdays{padding:5px 0 3px;color:var(--muted);font-size:8px;font-weight:800;text-align:center}.calendar__grid button{height:31px;padding:1px;display:flex;flex-direction:column;align-items:center;background:none;color:inherit;font-size:10px}.calendar__grid button span{width:23px;height:23px;border-radius:50%;display:grid;place-items:center}.calendar__grid button.outside{opacity:.3}.calendar__grid button.today span{box-shadow:inset 0 0 0 1px var(--accent);color:var(--accent);font-weight:900}.calendar__grid button.selected span{background:var(--accent);color:#fff;box-shadow:none;font-weight:900}.calendar__grid button i{width:3px;height:3px;margin-top:1px;border-radius:50%;background:var(--accent)}.calendar__grid button.selected i{background:#fff}.calendar__agenda{padding:13px 1px 5px}.calendar__agenda-title{margin-bottom:9px;display:flex;align-items:end;justify-content:space-between}.calendar__agenda-title small{display:block;color:var(--accent);font-size:8px;font-weight:900;text-transform:uppercase}.calendar__agenda-title h2{margin:2px 0 0;font-size:16px;text-transform:capitalize}.calendar__agenda-title>span{min-width:24px;height:24px;border-radius:8px;display:grid;place-items:center;background:var(--panel);font-size:10px;font-weight:800}.calendar__empty{min-height:145px;padding:19px;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:5px;border-radius:15px;background:var(--panel);color:var(--muted);text-align:center}.calendar__empty strong{color:inherit;font-size:13px}.calendar__empty span{max-width:220px;font-size:9px}.calendar__empty button{margin-top:4px;padding:8px 11px;border-radius:9px;display:flex;align-items:center;gap:4px;background:var(--accent);color:#fff;font-size:9px;font-weight:900}.calendar__event{width:100%;min-height:59px;margin-bottom:7px;padding:8px 9px;border-radius:13px;display:flex;align-items:center;gap:8px;background:var(--panel);text-align:left}.calendar__event>span{width:39px;text-align:right}.calendar__event b,.calendar__event small,.calendar__event strong{display:block}.calendar__event b{font-size:10px}.calendar__event small{color:var(--muted);font-size:8px}.calendar__event>i{width:3px;height:39px;border-radius:3px;background:var(--accent)}.calendar__event>div{min-width:0;flex:1}.calendar__event strong{overflow:hidden;font-size:11px;white-space:nowrap;text-overflow:ellipsis}.calendar__event div small{overflow:hidden;white-space:nowrap;text-overflow:ellipsis}.calendar__event>svg{color:var(--muted)}.calendar__auth{height:calc(100% - 65px);padding:35px;display:flex;flex-direction:column;align-items:center;justify-content:center;color:var(--muted);text-align:center}.calendar__auth svg{color:var(--accent)}.calendar__auth h2{margin:12px 0 4px;color:inherit;font-size:18px}.calendar__auth p{margin:0;font-size:10px;line-height:1.5}.calendar__detail,.calendar__form{position:absolute;inset:0;padding-top:47px;background:#11151b}.calendar--light .calendar__detail,.calendar--light .calendar__form{background:#fbfbfc}.calendar__detail>header,.calendar__form>header{height:54px;padding:6px 13px;display:grid;grid-template-columns:36px 1fr 36px;align-items:center;border-bottom:1px solid #ffffff12}.calendar__detail>header>strong{text-align:center;font-size:13px}.calendar__detail article{height:calc(100% - 54px);padding:22px 17px 35px;overflow-y:auto}.calendar__detail-icon{width:56px;height:56px;margin-bottom:13px;border-radius:17px;display:grid;place-items:center;background:linear-gradient(145deg,#ff7a67,var(--accent));color:white;box-shadow:0 9px 24px #ff405044}.calendar__detail article>small{color:var(--accent);font-size:8px;font-weight:900;text-transform:uppercase}.calendar__detail h1{margin:3px 0 20px;font-size:25px;line-height:1.12}.calendar__detail-row{margin-bottom:8px;padding:11px;border-radius:13px;display:flex;align-items:center;gap:10px;background:var(--panel)}.calendar__detail-row>svg{color:var(--accent)}.calendar__detail-row small,.calendar__detail-row strong{display:block}.calendar__detail-row small{color:var(--muted);font-size:8px}.calendar__detail-row strong{font-size:11px}.calendar__note{margin-top:14px;padding:13px;border-radius:13px;display:flex;align-items:flex-start;gap:9px;background:var(--panel)}.calendar__note svg{flex:none;color:var(--accent)}.calendar__note p{margin:0;color:var(--muted);font-size:10px;line-height:1.5;white-space:pre-wrap}.calendar__delete{width:100%;margin-top:18px;padding:10px;border-radius:11px;display:flex;align-items:center;justify-content:center;gap:5px;background:#ff4d5f1c;color:#ff6573;font-size:10px;font-weight:800}.calendar__form>header>div{text-align:center}.calendar__form header small,.calendar__form header strong{display:block}.calendar__form header strong{font-size:13px}.calendar__form>header>button:last-child{background:var(--accent);color:#fff}.calendar__form>form{height:calc(100% - 54px);padding:17px 15px 40px;overflow-y:auto}.calendar__form label{display:block;margin-bottom:13px;color:var(--muted);font-size:9px;font-weight:800}.calendar__form input,.calendar__form textarea{width:100%;margin-top:5px;padding:11px;border:1px solid #ffffff14;border-radius:11px;outline:0;background:var(--panel);font-size:12px}.calendar--light .calendar__form input,.calendar--light .calendar__form textarea{border-color:#00000010}.calendar__form textarea{height:104px;resize:none;line-height:1.45}.calendar__time-row{display:grid;grid-template-columns:1fr 1fr;gap:8px}.calendar__select{margin:-8px 0 13px;position:relative}.calendar__select>button{width:100%;padding:10px;border-radius:11px;display:flex;align-items:center;gap:8px;background:var(--panel);font-size:11px;text-align:left}.calendar__select>button span{flex:1}.calendar__select>button svg:first-child{color:var(--accent)}.calendar__select>button svg:last-child{transition:transform .18s}.calendar__select>button svg.open{transform:rotate(90deg)}.calendar__select>div{position:absolute;z-index:4;top:43px;right:0;left:0;padding:5px;border-radius:12px;background:#292e37;box-shadow:0 12px 35px #0008}.calendar--light .calendar__select>div{background:#fff}.calendar__select>div button{width:100%;padding:8px;border-radius:8px;display:flex;justify-content:space-between;background:none;font-size:10px;text-align:left}.calendar__select>div button.active{background:var(--accent);color:#fff}.calendar__error{margin:-4px 0 10px;color:#ff6976;font-size:9px}.calendar__save{width:100%;padding:11px;border-radius:11px;background:var(--accent);color:#fff!important;font-size:11px;font-weight:900}.calendar__save:disabled,.calendar__form>header>button:disabled{opacity:.45}
+</style>
diff --git a/frontend/testserver/index.cjs b/frontend/testserver/index.cjs
index 589af87..684d06d 100644
--- a/frontend/testserver/index.cjs
+++ b/frontend/testserver/index.cjs
@@ -134,6 +134,7 @@ let mockNotes = [
     updatedAt: Date.now() - 3_600_000,
   },
 ]
+let calendarEvents = []
 const deviceData = {}
 let mockMedia = [
   {
@@ -430,10 +431,65 @@ app.post('/api/:endpoint', (request, response) => {
     linkedAccount = null
     mockNotes = []
     mockMedia = []
+    calendarEvents = []
     for (const key of Object.keys(deviceData)) delete deviceData[key]
     response.json({ success: true })
     return
   }
+  if (endpoint.startsWith('calendar:') && !authenticated) {
+    response.json({ success: false, error: 'not_authenticated' })
+    return
+  }
+  if (endpoint === 'calendar:list') {
+    const startsAt = Number(request.body.startsAt) * 1000
+    const endsAt = Number(request.body.endsAt) * 1000
+    response.json({
+      success: true,
+      data: calendarEvents.filter(
+        (event) => event.endsAt >= startsAt && event.startsAt < endsAt,
+      ),
+    })
+    return
+  }
+  if (endpoint === 'calendar:create') {
+    const id = `calendar-${Date.now()}`
+    calendarEvents.push({
+      ...request.body,
+      endsAt: Number(request.body.endsAt) * 1000,
+      id,
+      remindedAt: null,
+      revision: 1,
+      startsAt: Number(request.body.startsAt) * 1000,
+    })
+    response.json({ success: true, data: { id } })
+    return
+  }
+  if (endpoint === 'calendar:update') {
+    const index = calendarEvents.findIndex(
+      (event) => event.id === request.body.id,
+    )
+    if (index < 0 || calendarEvents[index].revision !== request.body.revision) {
+      response.json({ success: false, error: 'conflict' })
+      return
+    }
+    calendarEvents[index] = {
+      ...calendarEvents[index],
+      ...request.body,
+      endsAt: Number(request.body.endsAt) * 1000,
+      remindedAt: null,
+      revision: calendarEvents[index].revision + 1,
+      startsAt: Number(request.body.startsAt) * 1000,
+    }
+    response.json({ success: true })
+    return
+  }
+  if (endpoint === 'calendar:delete') {
+    calendarEvents = calendarEvents.filter(
+      (event) => event.id !== request.body.id,
+    )
+    response.json({ success: true })
+    return
+  }
   if (endpoint === 'pages:list') {
     const query = String(request.body.search ?? '').toLowerCase()
     let items = pagesPosts
diff --git a/sky_phone/config/config.lua b/sky_phone/config/config.lua
index 0b6cd33..da559fe 100644
--- a/sky_phone/config/config.lua
+++ b/sky_phone/config/config.lua
@@ -102,3 +102,13 @@ Config.LocalPages = {
     Categories = { "recommendation", "wanted", "service", "event", "place", "community" },
     CityMarktSharesPerDay = 1,
 }
+
+Config.Calendar = {
+    TitleMaxLength = 120,
+    NoteMaxLength = 2000,
+    MaximumDurationSeconds = 7 * 24 * 60 * 60,
+    MaximumQuerySeconds = 370 * 24 * 60 * 60,
+    PastEditSeconds = 365 * 24 * 60 * 60,
+    FutureSeconds = 5 * 365 * 24 * 60 * 60,
+    ReminderPollSeconds = 15,
+}
diff --git a/sky_phone/config/locales/en.lua b/sky_phone/config/locales/en.lua
index 6794ec5..0e311a2 100644
--- a/sky_phone/config/locales/en.lua
+++ b/sky_phone/config/locales/en.lua
@@ -167,6 +167,9 @@ Locales["en"] = {
                     upload_failed = "The media upload failed.", upload_timeout = "The media upload timed out.",
                 },
             },
+            calendar = {
+                name = "Calendar", reminder = "Upcoming: {title}",
+            },
             clock = {
                 name = "Clock", lap = "Lap", minutes = "Minutes", add = "Add alarm", location = "Los Santos",
                 tabs = { world = "Clock", alarm = "Alarm", stopwatch = "Stopwatch", timer = "Timer" },
diff --git a/sky_phone/fxmanifest.lua b/sky_phone/fxmanifest.lua
index 0792bbf..1d30842 100644
--- a/sky_phone/fxmanifest.lua
+++ b/sky_phone/fxmanifest.lua
@@ -48,6 +48,7 @@ server_scripts {
     'source/server/marketplace.lua',
     'source/server/pages.lua',
     'source/server/media.lua',
+    'source/server/calendar.lua',
 }
 
 files {
diff --git a/sky_phone/source/client/main.lua b/sky_phone/source/client/main.lua
index 43b3ead..f682a90 100644
--- a/sky_phone/source/client/main.lua
+++ b/sky_phone/source/client/main.lua
@@ -55,6 +55,10 @@ local server_callbacks = {
     "pages:share-citymarkt",
     "pages:react",
     "pages:delete",
+    "calendar:list",
+    "calendar:create",
+    "calendar:update",
+    "calendar:delete",
     "sim:insert",
     "sim:eject",
     "contacts:list",
@@ -313,6 +317,13 @@ RegisterNetEvent("sky_phone:marketplace:new-message", function(data)
     SendNUIMessage({ type = "marketplace:new-message", data = data })
 end)
 
+RegisterNetEvent("sky_phone:calendar:reminder", function(data)
+    local calendar_locale = get_locale().Nui.Apps.calendar
+    data.title = calendar_locale.name
+    data.text = calendar_locale.reminder:gsub("{title}", tostring(data.eventTitle))
+    SendNUIMessage({ type = "calendar:reminder", data = data })
+end)
+
 RegisterNetEvent("sky_phone:sim:picker", function(data)
     sim_picker_open = true
     SetNuiFocus(true, true)
diff --git a/sky_phone/source/html/index.html b/sky_phone/source/html/index.html
index cad70e7..f24d72d 100644
--- a/sky_phone/source/html/index.html
+++ b/sky_phone/source/html/index.html
@@ -4,7 +4,7 @@
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>Sky Phone</title>
-    <script type="module" crossorigin src="./assets/sky-index-BZAEmZnj.js"></script>
+    <script type="module" crossorigin src="./assets/sky-index-Dj6qNtrv.js"></script>
     <link rel="stylesheet" crossorigin href="./assets/sky-index-DnowIFpD.css">
   </head>
   <body>
diff --git a/sky_phone/source/server/calendar.lua b/sky_phone/source/server/calendar.lua
new file mode 100644
index 0000000..5e2befa
--- /dev/null
+++ b/sky_phone/source/server/calendar.lua
@@ -0,0 +1,218 @@
+Bridge.Database.AfterMigration("sky_phone", function()
+local reminder_minutes = {
+    [0] = true,
+    [10] = true,
+    [30] = true,
+    [60] = true,
+    [1440] = true,
+}
+
+local function text_length(value)
+    return type(value) == "string" and utf8.len(value) or nil
+end
+
+local function affected_rows(result)
+    if type(result) == "number" then
+        return result
+    end
+    return type(result) == "table" and tonumber(result.affectedRows) or 0
+end
+
+local function event_dto(row)
+    return {
+        id = row.id,
+        title = row.title,
+        note = row.note,
+        startsAt = (tonumber(row.starts_at_unix) or 0) * 1000,
+        endsAt = (tonumber(row.ends_at_unix) or 0) * 1000,
+        reminderMinutes = row.reminder_minutes and tonumber(row.reminder_minutes) or nil,
+        remindedAt = row.reminded_at_unix and tonumber(row.reminded_at_unix) * 1000 or nil,
+        revision = tonumber(row.revision) or 1,
+    }
+end
+
+local function list_events(account_id, starts_at, ends_at)
+    local rows = Bridge.Database.Query([[
+        SELECT `id`, `title`, `note`, `reminder_minutes`, `revision`,
+            UNIX_TIMESTAMP(`starts_at`) AS `starts_at_unix`,
+            UNIX_TIMESTAMP(`ends_at`) AS `ends_at_unix`,
+            UNIX_TIMESTAMP(`reminded_at`) AS `reminded_at_unix`
+        FROM `sky_phone_calendar_events`
+        WHERE `account_id` = ?
+            AND `ends_at` >= FROM_UNIXTIME(?)
+            AND `starts_at` < FROM_UNIXTIME(?)
+        ORDER BY `starts_at`, `ends_at`, `id`
+        LIMIT 500
+    ]], { account_id, starts_at, ends_at })
+    local events = {}
+    for _, row in ipairs(rows) do
+        events[#events + 1] = event_dto(row)
+    end
+    return events
+end
+
+local function valid_range(starts_at, ends_at)
+    local now = os.time()
+    return starts_at >= now - Config.Calendar.PastEditSeconds
+        and starts_at <= now + Config.Calendar.FutureSeconds
+        and ends_at > starts_at
+        and ends_at - starts_at <= Config.Calendar.MaximumDurationSeconds
+end
+
+local function validate_event(data)
+    if type(data) ~= "table" then
+        return nil
+    end
+    local title_length = text_length(data.title)
+    local note_length = text_length(data.note)
+    local starts_at = math.floor(tonumber(data.startsAt) or 0)
+    local ends_at = math.floor(tonumber(data.endsAt) or 0)
+    local reminder = data.reminderMinutes
+    if not title_length
+        or title_length < 1
+        or title_length > Config.Calendar.TitleMaxLength
+        or not note_length
+        or note_length > Config.Calendar.NoteMaxLength
+        or not valid_range(starts_at, ends_at)
+        or (reminder ~= nil and not reminder_minutes[tonumber(reminder)])
+    then
+        return nil
+    end
+    return {
+        title = data.title,
+        note = data.note,
+        starts_at = starts_at,
+        ends_at = ends_at,
+        reminder_minutes = reminder == nil and nil or tonumber(reminder),
+    }
+end
+
+Bridge.Callbacks.Register("sky_phone:calendar:list", function(source, data)
+    local account, error_response = SkyPhone.RequireAccount(source)
+    if not account then
+        return error_response
+    end
+    local starts_at = math.floor(tonumber(data and data.startsAt) or 0)
+    local ends_at = math.floor(tonumber(data and data.endsAt) or 0)
+    if starts_at <= 0 or ends_at <= starts_at or ends_at - starts_at > Config.Calendar.MaximumQuerySeconds then
+        return { success = false, error = "invalid_range" }
+    end
+    return { success = true, data = list_events(account.id, starts_at, ends_at) }
+end)
+
+Bridge.Callbacks.Register("sky_phone:calendar:create", function(source, data)
+    if not SkyPhone.AllowOperation(source, "calendar_write", 60, 60) then
+        return { success = false, error = "rate_limited" }
+    end
+    local account, error_response = SkyPhone.RequireAccount(source)
+    if not account then
+        return error_response
+    end
+    local event = validate_event(data)
+    if not event then
+        return { success = false, error = "invalid_event" }
+    end
+    local ids = Bridge.Database.Query("SELECT UUID() AS `id`", {})
+    local id = ids[1] and ids[1].id
+    if type(id) ~= "string" then
+        error("[sky_phone] Database did not generate a calendar event id.")
+    end
+    Bridge.Database.Query([[
+        INSERT INTO `sky_phone_calendar_events`
+            (`id`, `account_id`, `title`, `note`, `starts_at`, `ends_at`, `reminder_minutes`)
+        VALUES (?, ?, ?, ?, FROM_UNIXTIME(?), FROM_UNIXTIME(?), ?)
+    ]], {
+        id,
+        account.id,
+        event.title,
+        event.note,
+        event.starts_at,
+        event.ends_at,
+        event.reminder_minutes,
+    })
+    return { success = true, data = { id = id } }
+end)
+
+Bridge.Callbacks.Register("sky_phone:calendar:update", function(source, data)
+    if not SkyPhone.AllowOperation(source, "calendar_write", 60, 60) then
+        return { success = false, error = "rate_limited" }
+    end
+    local account, error_response = SkyPhone.RequireAccount(source)
+    if not account then
+        return error_response
+    end
+    local event = validate_event(data)
+    if not event or type(data.id) ~= "string" then
+        return { success = false, error = "invalid_event" }
+    end
+    local revision = math.max(1, math.floor(tonumber(data.revision) or 0))
+    local result = Bridge.Database.Query([[
+        UPDATE `sky_phone_calendar_events`
+        SET `title` = ?, `note` = ?, `starts_at` = FROM_UNIXTIME(?),
+            `ends_at` = FROM_UNIXTIME(?), `reminder_minutes` = ?,
+            `reminded_at` = NULL, `revision` = `revision` + 1
+        WHERE `id` = ? AND `account_id` = ? AND `revision` = ?
+    ]], {
+        event.title,
+        event.note,
+        event.starts_at,
+        event.ends_at,
+        event.reminder_minutes,
+        data.id,
+        account.id,
+        revision,
+    })
+    if affected_rows(result) ~= 1 then
+        return { success = false, error = "conflict" }
+    end
+    return { success = true }
+end)
+
+Bridge.Callbacks.Register("sky_phone:calendar:delete", function(source, data)
+    if not SkyPhone.AllowOperation(source, "calendar_write", 60, 60) then
+        return { success = false, error = "rate_limited" }
+    end
+    local account, error_response = SkyPhone.RequireAccount(source)
+    if not account then
+        return error_response
+    end
+    if type(data) ~= "table" or type(data.id) ~= "string" then
+        return { success = false, error = "invalid_event" }
+    end
+    Bridge.Database.Query(
+        "DELETE FROM `sky_phone_calendar_events` WHERE `id` = ? AND `account_id` = ?",
+        { data.id, account.id }
+    )
+    return { success = true }
+end)
+
+CreateThread(function()
+    while true do
+        Wait(Config.Calendar.ReminderPollSeconds * 1000)
+        local due_events = Bridge.Database.Query([[
+            SELECT `id`, `account_id`, `title`, UNIX_TIMESTAMP(`starts_at`) AS `starts_at_unix`
+            FROM `sky_phone_calendar_events`
+            WHERE `reminder_minutes` IS NOT NULL
+                AND `reminded_at` IS NULL
+                AND DATE_SUB(`starts_at`, INTERVAL `reminder_minutes` MINUTE) <= CURRENT_TIMESTAMP
+                AND `starts_at` >= DATE_SUB(CURRENT_TIMESTAMP, INTERVAL 1 DAY)
+            ORDER BY `starts_at`
+            LIMIT 100
+        ]], {})
+        for _, event in ipairs(due_events) do
+            local result = Bridge.Database.Query([[
+                UPDATE `sky_phone_calendar_events`
+                SET `reminded_at` = CURRENT_TIMESTAMP
+                WHERE `id` = ? AND `reminded_at` IS NULL
+            ]], { event.id })
+            if affected_rows(result) == 1 then
+                SkyPhone.NotifyAccountDevices(event.account_id, "sky_phone:calendar:reminder", {
+                    eventId = event.id,
+                    eventTitle = event.title,
+                    startsAt = (tonumber(event.starts_at_unix) or 0) * 1000,
+                })
+            end
+        end
+    end
+end)
+end)
diff --git a/sky_phone/source/server/db_migrate.lua b/sky_phone/source/server/db_migrate.lua
index ebe9b11..40d063d 100644
--- a/sky_phone/source/server/db_migrate.lua
+++ b/sky_phone/source/server/db_migrate.lua
@@ -604,6 +604,31 @@ local schema = {
         },
         tableOptions = "ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci",
     },
+    {
+        name = "sky_phone_calendar_events",
+        columns = {
+            { name = "id", type = "CHAR(36) NOT NULL", characterSet = "ascii", collation = "ascii_bin" },
+            { name = "account_id", type = "BIGINT UNSIGNED NOT NULL" },
+            { name = "title", type = "VARCHAR(120) NOT NULL" },
+            { name = "note", type = "TEXT NOT NULL" },
+            { name = "starts_at", type = "DATETIME NOT NULL" },
+            { name = "ends_at", type = "DATETIME NOT NULL" },
+            { name = "reminder_minutes", type = "SMALLINT UNSIGNED NULL" },
+            { name = "reminded_at", type = "DATETIME NULL" },
+            { name = "revision", type = "INT UNSIGNED NOT NULL DEFAULT 1" },
+            { name = "created_at", type = "DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP" },
+            { name = "updated_at", type = "DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP" },
+        },
+        primaryKey = "id",
+        indexes = {
+            { name = "idx_sky_phone_calendar_account", columns = "(`account_id`, `starts_at`)" },
+            { name = "idx_sky_phone_calendar_reminders", columns = "(`reminded_at`, `starts_at`)" },
+        },
+        foreignKeys = {
+            { column = "account_id", references = "`sky_phone_accounts` (`id`) ON DELETE CASCADE" },
+        },
+        tableOptions = "ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci",
+    },
 }
 
 Bridge.Database.Migrate("sky_phone", schema)
diff --git a/sky_phone/sql/install.sql b/sky_phone/sql/install.sql
index 4c8eaa3..0c385c0 100644
--- a/sky_phone/sql/install.sql
+++ b/sky_phone/sql/install.sql
@@ -176,3 +176,21 @@ CREATE TABLE IF NOT EXISTS `sky_phone_call_entries` (
     FOREIGN KEY (`account_id`) REFERENCES `sky_phone_accounts` (`id`) ON DELETE CASCADE,
     FOREIGN KEY (`device_imei`) REFERENCES `sky_phone_devices` (`imei`) ON DELETE CASCADE
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
+
+CREATE TABLE IF NOT EXISTS `sky_phone_calendar_events` (
+    `id` CHAR(36) CHARACTER SET ascii COLLATE ascii_bin NOT NULL,
+    `account_id` BIGINT UNSIGNED NOT NULL,
+    `title` VARCHAR(120) NOT NULL,
+    `note` TEXT NOT NULL,
+    `starts_at` DATETIME NOT NULL,
+    `ends_at` DATETIME NOT NULL,
+    `reminder_minutes` SMALLINT UNSIGNED NULL,
+    `reminded_at` DATETIME NULL,
+    `revision` INT UNSIGNED NOT NULL DEFAULT 1,
+    `created_at` DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    `updated_at` DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
+    PRIMARY KEY (`id`),
+    KEY `idx_sky_phone_calendar_account` (`account_id`, `starts_at`),
+    KEY `idx_sky_phone_calendar_reminders` (`reminded_at`, `starts_at`),
+    FOREIGN KEY (`account_id`) REFERENCES `sky_phone_accounts` (`id`) ON DELETE CASCADE
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;