Comparison

Opus One vs Quarterdeck Pro

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

Head to head
About

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.

Highlights
  • 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
Features
Read 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/

About

Quarterdeck Pro

This app serves as a centralized workspace for professionals to manage tasks, notes, code snippets, finances, and projects. It offers features like priority task management, rich text notes, financial tracking, and project oversight, all synced across devices.

Highlights
  • Task management with priorities and deadlines
  • Rich text note-taking
  • Finance tracking for income and expenses
  • Code snippet storage
  • Project management
  • iCloud sync across devices
Features
Read full description

Quarterdeck is a notes app with Apple Intelligence built in — and it runs on your iPhone, not on someone's server. Summarize a long note. Pull the action items out of a meeting write-up and turn them into real tasks. Ask what your spending is telling you. All of it happens on-device, which means it works on a plane, and nothing you write is uploaded to be processed. WRITE THE WAY YOU ACTUALLY WORK • Rich text with headings, lists and checklists • Drop in photos and PDFs — they sit inline, where you put them • Dictate straight into a page and watch the words land as you speak • Scan a document with the camera and keep it as a real page, not a snapshot • Search finds words inside your images, not just the ones you typed • Lock a note behind Face ID or a PIN CAPTURE IT WHEREVER YOU ARE • Share a page from Safari and it arrives as a note, with a preview card • Home Screen widgets for today's tasks and one-tap capture • "Hey Siri, note this in Quarterdeck" • Everything syncs over iCloud, privately, across iPhone, iPad and Mac MORE THAN NOTES • Tasks — priorities, due dates, checklists, repeats • Agenda — your day and week, with real repeating events • Projects — plan work and track it to done • Finance — income, expenses, bills and budgets, with AI reading the trend • Code — a snippet library that explains any snippet back to you FREE, AND HONESTLY FREE Notes, tasks, agenda and projects are free forever — not a trial, not a countdown. You also get five Apple Intelligence runs a month at no charge, so you can judge it on your own notes. Quarterdeck Pro makes AI unlimited and adds dictation, document scanning, unlimited attachments, and the Finance and Code modules. Try Pro free for a week. PRIVACY Apple Intelligence runs on your device. Your notes sync through your own iCloud account. There is no Quarterdeck server, no account to create, and no analytics following you around. Requires an Apple Intelligence–capable device for the AI features. Everything else works on any iPhone running iOS 17 or later. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

Screenshots

Opus One4 screens
Quarterdeck Pro4 screens

Verdict

The call

The clearest difference is monetization model: Quarterdeck Pro at freemium against Opus One's subscription. Quarterdeck Pro also leads on update cadence (every 4 days vs every 3 weeks) and rating (5.0 vs 4.7). Opus One's advantage is ratings volume (973 vs 1) and device support (4 vs 2). On price, 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

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Opus One sells 2 in-app purchases, starting at $4.99 per month and Quarterdeck Pro sells 3 in-app purchases, starting at $7.99 per month. Whichever you choose, the download price is not the number that matters.

ReceptionRating · Positive reviews · Number of ratings

Quarterdeck Pro holds the better App Store score, 5.0 against 4.7. That said, the two scores are not equally well evidenced: Opus One has 973 ratings behind it against 1, so its average is the more settled of the two.

UpkeepUpdate frequency

Opus One ships an update every 3 weeks, Quarterdeck Pro every 4 days. The most recent releases landed on October 18, 2026 and October 4, 2026 respectively.

Scorecard6 real differences · 4 level
Opus One versus Quarterdeck Pro: the parameters behind the verdict, then further details
ParameterOpus OneQuarterdeck Pro
PriceFreeFree
Rating4.7 (973 ratings)5.0 (1 ratings) — better
Positive reviews65.7% of reviews—
Number of ratings973 — better1
Update frequencyEvery 3 weeksEvery 4 days — better
AdsNoNo
In-app purchasesYesYes
MonetizationSubscriptionFreemium — better
DevicesiPhone, iPad, iPod, Apple Watch — betteriPhone, iPad
Requires iOS15.0 — better17.0
Further details — not scored
Size187 MB9 MB
Age rating4+4+
DeveloperPISO 13, Inc.Dylan Dalmeida

Customer experience

Opus One

All ratings973 ratings
Positive93.6%
Neutral2.5%
Negative3.9%
Written reviews318 reviews
Positive65.7%
Neutral10.1%
Negative24.2%

Quarterdeck Pro

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%

Bugs and requests

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 more
  • Allow customization of UI and themes

Quarterdeck Pro

Not enough reviews yet to summarise bugs or requests.

In-app purchases

2 purchases

Opus One

Subscriptions2
  • Opus One Pro7 Days trial$4.991 Month
  • Opus One Professional7 Days trial$39.991 Year
3 purchases

Quarterdeck Pro

Subscriptions2
  • Monthly$7.991 Month
  • Yearly$49.991 Year
One-time1
  • Lifetime$89.99

Questions

Is Opus One free?
Opus One is free to download, with in-app purchases available.
Is Quarterdeck Pro free?
Quarterdeck Pro is free to download, with in-app purchases available.
Which has better reviews, Opus One or Quarterdeck Pro?
Quarterdeck Pro is rated higher. Opus One averages 4.7 out of 5 from 973 ratings, while Quarterdeck Pro averages 5.0 from 1 ratings.
Do Opus One or Quarterdeck Pro have ads?
Neither Opus One nor Quarterdeck Pro shows ads.
Which is updated more often, Opus One or Quarterdeck Pro?
Opus One ships an update every 3 weeks, and Quarterdeck Pro every 4 days. Most recently, Opus One was updated on October 18, 2026 and Quarterdeck Pro on October 4, 2026.

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