# O3 vs Shift Calendar

The clearest difference is in-app purchases: O3 at none against Shift Calendar's 8. O3 also leads on rating (5.0 vs 4.7) and iOS requirement (15.2 vs 17.0). Shift Calendar's advantage is update cadence (weekly vs every 12 months). On price, ratings volume, ads and device support there is nothing between them.

Both are free to download. Shift Calendar sells 8 in-app purchases, starting at $0.99 per 7 days. O3 asks for nothing beyond the download.

O3 holds the better App Store score, 5.0 against 4.7. Both are backed by a comparable volume of ratings — 2 and 3 respectively.

O3 ships an update every 12 months, Shift Calendar weekly. The most recent releases landed on November 2, 2026 and November 4, 2026 respectively.

## The numbers

| Metric | O3 | Shift Calendar |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (2 ratings)](https://appshunter.io/ios/app/o3/id1365145779/reviews)** | [4.7 (3 ratings)](https://appshunter.io/ios/app/shift-calendar-shiftpro/id6736994383/reviews) |
| Number of ratings | 2 | **3** |
| Positive reviews | — | 87.8% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 12 months | **Weekly** |
| Monetization | **Free** | Free with in-app purchases |
| Size | 7 MB | 165 MB |
| Requires iOS | **15.2** | 17.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Delta Intelligent Building Technologies (Canada) Inc.](https://appshunter.io/developer/1039551888) | [Andrea Agostino Cataldo](https://appshunter.io/developer/1774275152) |

## What reviewers say

### O3

[App page](https://appshunter.io/ios/app/o3/id1365145779)

Control your smart home environment with this app. Create custom profiles for different activities to manage HVAC, lighting, and blinds. Optimize energy usage and personalize your space for comfort and productivity.

**Highlights:** Activity-based room profiles, Energy-saving eco modes, HVAC control, Lighting dimming, Blind adjustment, Bluetooth connectivity

**In-app purchases:** none


### Shift Calendar

[App page](https://appshunter.io/ios/app/shift-calendar-shiftpro/id6736994383)

Organize your work schedule with a customizable calendar designed for shift workers. Track absences, monitor work hours with detailed statistics, and generate exportable reports. Features a dark mode for comfortable viewing.

**Highlights:** Customized shift scheduling, Complete absence management, Advanced reporting, Exportable reports, Dark mode

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (8)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Weekly | $0.99 | per 7 days |
| Monthly | $1.99 | per month |
| Weekly | $1.99 | per 7 days |
| Monthly | $3.99 | per month |
| Monthly | $3.99 | per month |
| Annual | $12.99 | per year |
| Annual | $19.99 | per year |
| Annual | $19.99 | per year |

**What reviewers like**

- 👍 User-friendly interface
- 🚀 Efficient shift planning
- 📊 Detailed reporting
- 🎨 Customizable calendar
- 💻 Intuitive and easy to use

**What reviewers complain about**

- 🔧 Limited category customization

**Requested features**

- Widget support
- Larger font size for exports


## Frequently asked questions

### Is O3 free?

O3 is free to download, with no in-app purchases.

### Is Shift Calendar free?

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

### Which has better reviews, O3 or Shift Calendar?

O3 is rated higher. O3 averages 5.0 out of 5 from 2 ratings, while Shift Calendar averages 4.7 from 3 ratings.

### Do O3 or Shift Calendar have ads?

Neither O3 nor Shift Calendar shows ads.

### Which is updated more often, O3 or Shift Calendar?

O3 ships an update every 12 months, and Shift Calendar weekly. Most recently, O3 was updated on November 2, 2026 and Shift Calendar on November 4, 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.*