Calendars vs Availability Sync
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
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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
Availability Sync
Easily share your free time slots for meetings and appointments. This app integrates with your existing calendars and allows for customized sharing messages and professional calendar invites. Streamline your scheduling process and avoid back-and-forth communication.
- Instant availability sharing
- Calendar integration (iOS, Google, Outlook)
- Customizable sharing messages
- Professional calendar invitations
- Multiple time slot selection
- Time zone management
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Availability Sync: Share Your Availability Instantly Transform how you coordinate schedules and share your availability. Whether you're planning meetings, managing appointments, or coordinating with others, share your free time slots in seconds. FEATURES: Smart Sharing - Share available time slots instantly via text or calendar invites - Customize sharing messages for different recipients - Generate professional calendar invitations - Create personalized event titles and descriptions - Share across any messaging platform - Select multiple time slots in one go Calendar Integration - Sync with iOS, Google, and Outlook calendars - View all your calendars in one unified interface - Real-time updates as your schedule changes - Instant conflict detection Availability Management - Select and share multiple time slots at once - Customize work week and weekend schedules - Set preferred meeting durations - Define working hours for different days - Manage time zones effortlessly Time Slot Controls - Choose between 30-minute to 2-hour slots - Select entire days or specific times - Quick bulk selection options - Filter by morning, afternoon, or evening - View calendar conflicts instantly Professional Customization - Personalize event titles and descriptions - Create custom sharing messages - Choose between text or calendar format - Adjust time zone displays for recipients - Flexible date and time formats Perfect for: - Professionals sharing meeting availability - Teams coordinating across time zones - Freelancers managing client appointments - Anyone tired of back-and-forth scheduling emails Additional Features: - Support for light and dark modes - Multiple visual themes - Quick event creation - Privacy-focused design - Regular updates and improvements Download Availability Sync today and transform how you share your availability. No more endless email chains or scheduling confusion - just simple, efficient calendar sharing. Take control of your schedule sharing with Availability Sync.
Screenshots
Verdict
The clearest difference is in-app purchases: Availability Sync at none against Calendars's 20. Availability Sync also leads on review sentiment (67% vs 55%). Calendars's advantage is ratings volume (122K vs 5) and rating (4.7 vs 4.4). On price, update cadence, ads and iOS requirement 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. Availability Sync asks for nothing beyond the download.
Calendars holds the better App Store score, 4.7 against 4.4. That said, the two scores are not equally well evidenced: Calendars has 122K ratings behind it against 5, so its average is the more settled of the two. Written reviews complicate that: 55% of Calendars's written reviews are positive against 67% of Availability Sync's, so the app with the better star average is not the one people write more warmly about.
Calendars ships an update every 11 days, Availability Sync weekly. The most recent releases landed on September 24, 2026 and June 2, 2026 respectively.
| Parameter | Calendars | Availability Sync |
|---|---|---|
| Price | Free | Free |
| Rating | 4.7 (122K ratings) — better | 4.4 (5 ratings) |
| Positive reviews | 55.4% of reviews | 66.7% of reviews — better |
| Number of ratings | 122K — better | 5 |
| Update frequency | Every 11 days | Weekly — better |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Free with in-app purchases | Free — better |
| Best chart rank | #105 — better | — |
| Devices | iPhone, iPad, Mac, Apple Watch — better | iPhone, iPad |
| Requires iOS | 18.2 | 17.5 — better |
| Further details — not scored | ||
| Size | 407 MB | 10 MB |
| Age rating | 4+ | 4+ |
| Developer | Readdle Technologies Limited | David Fuerst |
Customer experience
Calendars
Availability Sync
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
Availability Sync
Not enough reviews yet to summarise bugs or requests.
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
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- 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
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- 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
Availability Sync
No in-app purchases
Questions
Is Calendars free?
Is Availability Sync free?
Which has better reviews, Calendars or Availability Sync?
Do Calendars or Availability Sync have ads?
Which is updated more often, Calendars or Availability Sync?
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