Comparison

O2 Calendar vs Mega Calendar

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

O2 Calendar

Manage your schedule with this app, offering tools for events, appointments, notes, and daily tasks. Set custom reminders for your important activities and organize your day effectively.

Highlights
  • Event creation and management
  • Customizable event reminders
  • Daily task reminders
  • Note-taking functionality
  • Appointment scheduling
Features
Read full description

O2 Calendar là công cụ tốt nhất để quản lý công việc của bạn: Lịch, Sự kiện, cuộc hẹn, ghi chú và công việc hàng ngày. Tính năng, đặc điểm - Tạo và quản lý sự kiện - Nhắc nhở tùy chỉnh cho Sự kiện - Tạo nhắc nhở hàng ngày

About

Mega Calendar

Organize your schedule with detailed daily planning, recurring event setup, and customizable reminders. Create travel itineraries, manage to-do lists with notifications, and access all features offline. Personalize notification sounds to distinguish between events.

Highlights
  • Detailed daily planning
  • Recurring event setup
  • Customizable reminders
  • Travel itinerary creation
  • To-do list management
  • Offline functionality
  • Customizable notification sounds
Features
Read full description

Mega Calendar: Your Ultimate Time Management Companion Plan your day or multiple days in advance. Effortlessly schedule your day or multiple days in detail, ensuring you stay organized and never miss an important event or activity. SHARED GROUP CALENDARS - PLAN TOGETHER WITH THE PEOPLE AROUND YOU This is what makes Mega Calendar truly special - a feature most calendar apps simply don't have. Create a shared group, invite the people around you, and everyone sees the same plan update in real time. - Create a group and invite family, friends, roommates or teammates with a simple invite code - Share any plan or event to the group with a single tap - Everyone stays in sync automatically - changes appear instantly for all members - See who created or updated each shared event - Perfect for family schedules, trips, study groups, team projects and shared chores Stop juggling screenshots and group chats - keep everyone literally on the same page. Set up recurring events. Simplify reminder scheduling by repeating events daily, weekly, monthly or annually. Get timely reminders for upcoming appointments and event starts. Never forget or miss an appointment again with customizable reminders. Receive alerts well in advance of event start times. Plan trips with family or friends. Create comprehensive travel plans including itineraries, accommodations, sightseeing and more - then share them with your group so everyone is ready. To-do lists and notifications. Stay on top of your tasks by creating to-do lists and receiving notifications before each task is due. Offline functionality. Plan and manage your time anytime, anywhere — even without an internet connection. Customize notification sounds. Distinguish events using different notification sounds for each event or plan. Download Mega Calendar today and start organizing your time - together. Never miss another event again. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

Screenshots

O2 Calendar4 screens
Mega Calendar4 screens

Verdict

The call

The clearest difference is review sentiment: Mega Calendar at 100% against O2 Calendar's 50%. O2 Calendar's advantage is in-app purchases (none vs 3) and ads (none vs shown). On price and device support there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Mega Calendar sells 3 in-app purchases, starting at $0.99 per month. O2 Calendar asks for nothing beyond the download.

UpkeepUpdate frequency

O2 Calendar ships an update every 4 days, Mega Calendar every 2 weeks. The most recent releases landed on November 3, 2026 and November 4, 2026 respectively.

Scorecard6 real differences · 4 level
O2 Calendar versus Mega Calendar: the parameters behind the verdict, then further details
ParameterO2 CalendarMega Calendar
PriceFreeFree
Rating—5.0 (1 ratings) — better
Positive reviews50.0% of reviews100.0% of reviews — better
Number of ratings—1 — better
Update frequencyEvery 4 days — betterEvery 2 weeks
AdsNo — betterYes
In-app purchasesNo — betterYes
MonetizationFree — betterFree with in-app purchases
DevicesiPhone, iPad, iPod — betteriPhone, iPod
Requires iOS9.0 — better15.0
Further details — not scored
Size52 MB103 MB
Age rating4+4+
DeveloperO2 VN Tech.,JSCVU THANH

Customer experience

O2 Calendar

Written reviews2 reviews
Positive50.0%
Neutral0.0%
Negative50.0%

Mega Calendar

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews16 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

None

O2 Calendar

No in-app purchases

3 purchases

Mega Calendar

Subscriptions2
  • Monthly$0.991 Month
  • Yearly$3.991 Year
One-time1
  • Lifetime$7.99

Questions

Is O2 Calendar free?
O2 Calendar is free to download, with no in-app purchases.
Is Mega Calendar free?
Mega Calendar is free to download, with in-app purchases available.
Do O2 Calendar or Mega Calendar have ads?
Mega Calendar shows ads; O2 Calendar does not.
Which is updated more often, O2 Calendar or Mega Calendar?
O2 Calendar ships an update every 4 days, and Mega Calendar every 2 weeks. Most recently, O2 Calendar was updated on November 3, 2026 and Mega Calendar on November 4, 2026.

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