# Calendars vs Availability Sync

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.

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 25, 2026 and June 2, 2026 respectively.

## The numbers

| Metric | Calendars | Availability Sync |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.7 (122K ratings)](https://appshunter.io/ios/app/calendars-schedule-planner/id608834326/reviews)** | [4.4 (5 ratings)](https://appshunter.io/ios/app/availability-sync/id6670766226/reviews) |
| Number of ratings | **122K** | 5 |
| Positive reviews | 55.4% of reviews | **66.7% of reviews** |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 11 days | **Weekly** |
| Monetization | Free with in-app purchases | **Free** |
| Best chart rank | **#102** | — |
| Size | 407 MB | 10 MB |
| Requires iOS | 18.2 | **17.5** |
| Devices | **iPhone, iPad, Mac, Apple Watch** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Readdle Technologies Limited](https://appshunter.io/developer/285035419) | [David Fuerst](https://appshunter.io/developer/1754806202) |

## What reviewers say

### Calendars

[App page](https://appshunter.io/ios/app/calendars-schedule-planner/id608834326)

**Currently charting:** #102 Top Free · Productivity, #118 Top Grossing · Productivity (US App Store)

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.

**Highlights:** Calendar, task, and habit management, Daily, weekly, and monthly views, Natural language event creation, To-do list organization, Cross-device syncing, Meeting platform integration

**Features:** Family Sharing, Apple Watch app, Vision Pro support

**In-app purchases (18)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Calendars PRO 1 Month | $3.99 | per month |
| Calendars by Readdle: Interesting Calendars | $3.99 | per year |
| Calendars PRO 1 Month | $3.99 | per month |
| Calendars PRO 1 Year | $19.99 | per year |
| Calendars PRO 1 Year | $19.99 | per year |
| Calendars PRO 1 Year | $19.99 | per year |
| Calendars PRO 1 Year | $19.99 | per year |
| Calendars PRO 1 Year | $21.99 | per year |
| Calendars PRO 1 Year | $29.99 | per year |
| Calendars PRO Lifetime | Free | one-time |
| Invites & Attendees Upgrade | $1.99 | one-time |
| Smart Input Upgrade | $1.99 | one-time |
| Full Upgrade | $4.99 | one-time |
| Interesting Calendars | $5.99 | one-time |
| My schedule planner, Organizer | $6.99 | one-time |
| Full Pack | $12.99 | one-time |
| Reminders & Calendars | $19.99 | one-time |
| Recurring Events | $31.99 | one-time |

**What reviewers like**

- 🌟 Excellent calendar app
- 👍 Easy to use and organize
- 🎨 Helpful color-coding
- 📆 Seamless integration with other calendars
- 🗓️ Detailed monthly/weekly views

**What reviewers complain about**

- 🐛 Occasional glitches and data loss
- 💰 Concerns over subscription model
- 🕰️ Cumbersome date/time selection process
- 🔍 Limited location search functionality
- 🔄 Sync issues between devices

**Reported bugs**

- Disappearing events and appointments
- Upgrade process causing data loss
- Freezing and crashing on certain devices

**Requested features**

- 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

[App page](https://appshunter.io/ios/app/availability-sync/id6670766226)

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.

**Highlights:** Instant availability sharing, Calendar integration (iOS, Google, Outlook), Customizable sharing messages, Professional calendar invitations, Multiple time slot selection, Time zone management

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Calendars free?

Calendars is free to download, with in-app purchases available.

### Is Availability Sync free?

Availability Sync is free to download, with no in-app purchases.

### Which has better reviews, Calendars or Availability Sync?

Calendars is rated higher. Calendars averages 4.7 out of 5 from 122K ratings, while Availability Sync averages 4.4 from 5 ratings.

### Do Calendars or Availability Sync have ads?

Neither Calendars nor Availability Sync shows ads.

### Which is updated more often, Calendars or Availability Sync?

Calendars ships an update every 11 days, and Availability Sync weekly. Most recently, Calendars was updated on September 25, 2026 and Availability Sync on June 2, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*