# MyCircadianApp vs Project Function

The clearest difference is in-app purchases: Project Function at none against MyCircadianApp's 7. On price, update cadence, ads and device support there is nothing between them.

Both are free to download. MyCircadianApp sells 7 in-app purchases, starting at $3.99 per month. Project Function asks for nothing beyond the download.

MyCircadianApp ships an update every 4 weeks, Project Function every 6 weeks. The most recent releases landed on August 29, 2026 and September 22, 2026 respectively.

## The numbers

| Metric | MyCircadianApp | Project Function |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.9 (264 ratings)](https://appshunter.io/ios/app/mycircadianapp/id6538168795/reviews)** | — |
| Number of ratings | **264** | — |
| Positive reviews | 98.6% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | **Every 4 weeks** | Every 6 weeks |
| Monetization | Free with in-app purchases | — |
| Size | 56 MB | 181 MB |
| Requires iOS | **15.1** | 15.5 |
| Devices | iPhone, iPad, iPod | **iPhone, iPad, iPod, Apple Watch** |
| Age rating | 12+ | 4+ |
| Developer | [Sarah Kleiner Wellness](https://appshunter.io/developer/1756991836) | [Project Function LLC](https://appshunter.io/developer/1790112444) |

## What reviewers say

### MyCircadianApp

[App page](https://appshunter.io/ios/app/mycircadianapp/id6538168795)

Optimize your health by tracking sunlight exposure, UV index, and vitamin D synthesis. Log sun sessions, monitor light levels, and receive personalized guidance based on your skin type, weather, and location. Enhance well-being and boost mood by syncing with natural light cycles.

**Highlights:** Sunlight exposure tracking, UV index monitoring, Vitamin D synthesis tracking, Circadian rhythm monitoring, Personalized guidance, Sunrise/sunset compass, Lux meter

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

**In-app purchases (7)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Monthly | $3.99 | per month |
| Monthly | $3.99 | per month |
| Yearly | $36.00 | per year |
| Yearly | $36.00 | per year |
| Lifetime | $99.00 | one-time |
| Lifetime | $179.00 | one-time |
| Lifetime | $199.00 | one-time |

**What reviewers like**

- 🌟 Comprehensive features
- 👍 User-friendly interface
- 🌞 Helpful for circadian health
- 📊 Detailed data and tracking
- 🎨 Aesthetically pleasing design

**What reviewers complain about**

- 🔍 Could use more educational content
- 📱 Occasional glitches or bugs reported

**Reported bugs**

- Login screen freezes
- Incompatibility with older devices

**Requested features**

- Ability to manually log sun sessions and vitamin D sources
- Option to view upcoming day's sunrise/sunset times


### Project Function

[App page](https://appshunter.io/ios/app/project-function/id6740467390)

**Features:** Apple Wallet, Apple Watch app

**In-app purchases:** none


## Frequently asked questions

### Is MyCircadianApp free?

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

### Is Project Function free?

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

### Do MyCircadianApp or Project Function have ads?

Neither MyCircadianApp nor Project Function shows ads.

### Which is updated more often, MyCircadianApp or Project Function?

MyCircadianApp ships an update every 4 weeks, and Project Function every 6 weeks. Most recently, MyCircadianApp was updated on August 29, 2026 and Project Function on September 22, 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.*