# OpEvol vs SkyLetter

The clearest difference is in-app purchases: SkyLetter at none against OpEvol's 1. SkyLetter also leads on update cadence (fortnightly vs every 22 months) and iOS requirement (12.0 vs 26.0). On price, review sentiment, ads and device support there is nothing between them.

Both are free to download. OpEvol sells 1 in-app purchase, starting at $6.99 per year. SkyLetter asks for nothing beyond the download.

OpEvol ships an update every 22 months, SkyLetter fortnightly. The most recent releases landed on September 30, 2026 and October 6, 2026 respectively.

## The numbers

| Metric | OpEvol | SkyLetter |
| --- | --- | --- |
| Price | Free | Free |
| Positive reviews | **27.3% of reviews** | 25.0% of reviews |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 22 months | **Fortnightly** |
| Monetization | Paid | **Free** |
| Size | 3 MB | 45 MB |
| Requires iOS | 26.0 | **12.0** |
| Devices | **iPhone, iPad, Apple TV** | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Muddlegeist](https://appshunter.io/developer/701677888) | [Kiyotaka Watanabe](https://appshunter.io/developer/1408976233) |

## What reviewers say

### OpEvol

[App page](https://appshunter.io/ios/app/opevol/id788355019)

Experience a dynamic, ever-changing display of psychedelic visuals inspired by 1960s Op Art. This app creates animated fields of geometric colors and contrasts for passive viewing or interactive play.

**Highlights:** Animated geometric patterns, Op Art inspired visuals, Psychedelic color displays, Interactive visual play, Air Display compatibility

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| OpEvol Annual Subscription | $6.99 | per year |


### SkyLetter

[App page](https://appshunter.io/ios/app/skyletter/id1469768088)

Create personalized messages drawn in the sky with airplane contrails. Share your creations as videos or photos on social media, perfect for sending unique greetings or declarations.

**Highlights:** Draw messages in the sky with contrails, Share creations as video or photo, Personalize messages for friends, Unique social media content

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is OpEvol free?

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

### Is SkyLetter free?

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

### Do OpEvol or SkyLetter have ads?

Neither OpEvol nor SkyLetter shows ads.

### Which is updated more often, OpEvol or SkyLetter?

OpEvol ships an update every 22 months, and SkyLetter fortnightly. Most recently, OpEvol was updated on September 30, 2026 and SkyLetter on October 6, 2026.

---

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