Calendars vs Opus One
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Calendars
This app combines a calendar, task manager, daily planner, and habit tracker. It helps users plan their day, build habits, boost productivity, and stay organized with seamless syncing across all Apple devices. Features include event creation, to-do list management, natural language input, and integration with popular meeting platforms.
- Calendar, task, and habit management
- Daily, weekly, and monthly views
- Natural language event creation
- To-do list organization
- Cross-device syncing
- Meeting platform integration
Read full descriptionHide full description
Calendars by Readdle is the all-in-one calendar, task manager, daily planner, and habit tracker — seamlessly working across all your Apple devices: Mac, iPhone, iPad, and Apple Watch. Plan your day, build better habits, boost productivity, and stay organized with powerful features and smooth sync between all your devices. What you can do with Calendars: • View and manage your calendar with daily, weekly, and monthly views • Create events, set reminders, and never miss important dates • Use the built-in agenda planner to focus on what matters most • Organize your to-do list and manage your tasks with ease • Quickly add events or to-do items using natural language • Build routines and track your habits to stay consistent • Take a guided productivity course to improve time management and focus • Sync across devices with Google Calendar, iCloud, and more • Customize your planner calendar with color coding and widgets • Join Zoom, Google Meet, or GoToMeeting directly from your calendar • Stay in control of your time, wherever you are Whether you're planning a busy workday, building new habits, or working on personal growth, Calendars brings everything together to help you own your time — across all your Apple devices. Privacy Policy: https://readdle.com/calendars/legal/privacy Terms of Service: https://readdle.com/calendars/legal/terms Have questions, comments, or issues? Don’t hesitate to reach out to us at http://readdle.com/contact
Opus One
This app helps you manage tasks and notes with a paperlike interface. Organize your day with daily task lists, schedules, and notes, and use a master task section to capture all your to-dos. Features include drag-and-drop reordering, event integration, and customizable notes.
- Master Task section
- Daily Task lists with status, priority, and notes
- Daily Schedule and Event integration
- Daily Notes with customizable text formatting
- Drag and drop task reordering
- Cloud synchronization
- Sketch drawing canvas
Read full descriptionHide full description
Opus One is a real day planner, not another to-do app. Each day gets its own page — tasks with A/B/C priorities, your schedule, and notes — on a planner that looks and feels like paper. Plan on iPhone, iPad, and Mac, and it all stays in sync. YOUR DAY ON ONE PAGE • Daily Tasks with A/B/C priorities, status, notes, and alarms. • A schedule that shows your Calendar events alongside your tasks. • Drag a task onto the schedule — with task durations, the end time fills in automatically. • Daily Notes with photos, PDFs, checklists, and audio. • Today's weather and a daily quote, right on the page. PLAN BEYOND TODAY • Master Tasks: everything on your mind in one list, no due date required. • Goals with timelines, photos, and progress you can see. • Roles: review the areas of your life each week so nothing important gets crowded out. • Mission, Values, and Vision pages to keep the big picture one tap away. • Meeting Planner for agendas, decisions, and next steps. NOTES AND JOURNALS • Rich notes with fonts, colors, tags, and your own custom sections. • Sketch and handwrite with Apple Pencil. • Journals with 25 covers to choose from, plus a guided Gratitude Journal. IT GOES WHERE YOU GO • Home Screen widgets for today's tasks, your mission, your values, and daily quotes. • Live Activities keep today's tasks on your Lock Screen. • Add a task from Control Center, or ask Siri. • Apple Watch app to see your day and check off tasks from your wrist. • iCloud sync across iPhone, iPad, and Mac. MAKE IT YOURS • Planner themes, including seasonal ones. • Task-complete sounds and rewards for finishing what you planned. • Color-coded categories and repeating rules with advanced options. OPUS ONE PRO The core planner is free. Opus One Pro adds cloud sync across all your devices, weather, attachments (images, PDFs, audio), Apple Pencil sketching, categories, repeating rules, Goals, Siri, and themes. One subscription covers iPhone, iPad, and Mac on the same iCloud account. Available yearly or monthly. Subscription details: Payment is charged to your Apple Account at confirmation of purchase. The subscription renews automatically unless auto-renew is turned off at least 24 hours before the end of the current period, and your account is charged for renewal within 24 hours before the period ends. Manage or cancel in your Account Settings. Privacy Policy: https://piso13.com/privacy-policy-2/ Terms of Service: https://piso13.com/terms-of-service/
Screenshots
Verdict
The clearest difference is monetization model: Calendars at free with in-app purchases against Opus One's subscription. Calendars also leads on ratings volume (122K vs 978) and update cadence (weekly vs every 3 weeks). Opus One's advantage is review sentiment (66% vs 56%) and iOS requirement (15.0 vs 18.2). On price, rating, ads and in-app purchases 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
Both are free to download. Calendars sells 18 in-app purchases, starting at $3.99 per month and Opus One sells 2 in-app purchases, starting at $4.99 per month. Whichever you choose, the download price is not the number that matters.
On the App Store both sit at effectively the same score — 4.7 for Calendars against 4.7 for Opus One. That said, the two scores are not equally well evidenced: Calendars has 122K ratings behind it against 978, so its average is the more settled of the two. Written reviews are what separate them: 56% of Calendars's written reviews are positive against 66% of Opus One's.
Calendars ships an update weekly, Opus One every 3 weeks. The most recent releases landed on October 28, 2026 and October 26, 2026 respectively.
| Parameter | Calendars | Opus One |
|---|---|---|
| Price | Free | Free |
| Rating | 4.7 (122K ratings) — better | 4.7 (978 ratings) |
| Positive reviews | 55.8% of reviews | 65.7% of reviews — better |
| Number of ratings | 122K — better | 978 |
| Update frequency | Weekly — better | Every 3 weeks |
| Ads | No | No |
| In-app purchases | Yes | Yes |
| Monetization | Free with in-app purchases — better | Subscription |
| Best chart rank | #117 — better | — |
| Devices | iPhone, iPad, Mac, Apple Watch | iPhone, iPad, iPod, Apple Watch |
| Requires iOS | 18.2 | 15.0 — better |
| Further details — not scored | ||
| Size | 412 MB | 187 MB |
| Age rating | 4+ | 4+ |
| Developer | Readdle Technologies Limited | PISO 13, Inc. |
Customer experience
Calendars
Opus One
User reviews
Calendars
From 122K App Store ratingsWhat we love
- 🌟 Excellent calendar app
- 👍 Easy to use and organize
- 🎨 Helpful color-coding
- 📆 Seamless integration with other calendars
- 🗓️ Detailed monthly/weekly views
Room to improve
- 🐛 Occasional glitches and data loss
- 💰 Concerns over subscription model
- 🕰️ Cumbersome date/time selection process
- 🔍 Limited location search functionality
- 🔄 Sync issues between devices
Opus One
From 978 App Store ratingsWhat we love
- 🚀 Life changing
- 👍 Great app and support
- 👍 Integrates well with iPhone
- 👍 Keeps me organized and efficient
- 👍 Seamless sync across devices
Room to improve
- 🐛 Sync issues and reliability problems
- 🐛 Lost data and app crashes
- 🔒 Concerns about free trial sign-ups
- 🔒 Difficult to cancel subscription
- 👎 Lacks weekly/monthly views
Bugs and requests
Calendars
Reported bugs
3 issues- Disappearing events and appointments
- Upgrade process causing data loss
- Freezing and crashing on certain devices
Requested features
5 requests- Recurring events for free users
- Customizable widgets and app icons
- Ability to archive/restore past events
- Improved Apple Watch integration
- Shared calendars and family management
Opus One
Reported bugs
4 issues- Sync issues between devices
- App crashes and data loss
- Keyboard not working on iPad
- Distorted font in calendar view
Requested features
6 requests- Add weekly and monthly views
- Improve Apple Pencil support
- Add project management features
- Integrate with more calendar/task apps
- Provide better training and tutorials
Show 1 moreShow fewer
- Allow customization of UI and themes
In-app purchases
Calendars
- Calendars PRO 1 Month$3.991 Month
- Calendars by Readdle: Interesting Calendars1 Month trial$3.991 Year
- Calendars PRO 1 Month7 Days trial$3.991 Month
Show 6 moreShow fewer
- Calendars PRO 1 Year3 Months trial$19.991 Year
- Calendars PRO 1 Year7 Days trial2 variants$19.991 Year
- Calendars PRO 1 Year1 Year trial$19.991 Year
- Calendars PRO 1 Year14 Days trial$19.991 Year
- Calendars PRO 1 Year7 Days trial$21.991 Year
- Calendars PRO 1 Year7 Days trial$29.991 Year
- Calendars PRO LifetimeFree
- Invites & Attendees Upgrade$1.99
- Smart Input Upgrade$1.99
Show 6 moreShow fewer
- Full Upgrade$4.99
- Interesting Calendars$5.99
- My schedule planner, Organizer$6.99
- Full Pack$12.99
- Reminders & Calendars$19.99
- Recurring Events$31.99
Opus One
- Opus One Pro7 Days trial$4.991 Month
- Opus One Professional7 Days trial$39.991 Year
Questions
Is Calendars free?
Is Opus One free?
Which has better reviews, Calendars or Opus One?
Do Calendars or Opus One have ads?
Which is updated more often, Calendars or Opus One?
Other comparisons















