# C vs SIONYX

The clearest difference is price: SIONYX at Free against C's $2.99. SIONYX also leads on rating (2.7 vs 1.0) and review sentiment (27% vs 0%). C's advantage is iOS requirement (13.0 vs 15.6). On ads, in-app purchases and device support there is nothing between them.

SIONYX is free to download; C costs $2.99 up front. Neither carries in-app purchases, so what you see is what you pay.

SIONYX holds the better App Store score, 2.7 against 1.0. That said, the two scores are not equally well evidenced: SIONYX has 15 ratings behind it against 1, so its average is the more settled of the two. Written reviews point the same way: 0% of C's written reviews are positive against 27% of SIONYX's.

C ships an update every 14 months, SIONYX every 5 months. The most recent releases landed on November 1, 2026 and October 6, 2026 respectively.

## The numbers

| Metric | C | SIONYX |
| --- | --- | --- |
| Price | $2.99 | **Free** |
| Rating | [1.0 (1 ratings)](https://appshunter.io/ios/app/c-measure/id397314427/reviews) | **[2.7 (15 ratings)](https://appshunter.io/ios/app/sionyx/id1642888573/reviews)** |
| Number of ratings | 1 | **15** |
| Positive reviews | 0.0% of reviews | **27.3% of reviews** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 14 months | **Every 5 months** |
| Monetization | Paid | **Free** |
| Size | 4 MB | 128 MB |
| Requires iOS | **13.0** | 15.6 |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [alpha prompt co.,ltd.](https://appshunter.io/developer/391698490) | [SiOnyx, LLC](https://appshunter.io/developer/1418868781) |

## What reviewers say

### C

[App page](https://appshunter.io/ios/app/c-measure/id397314427)

This app analyzes photographs to display the color of any point in XYZ and L*a*b* color spaces. It also allows for measuring the distance between two colors within the L*a*b* color space. Calibration options are available for matching camera characteristics and photography environments.

**Highlights:** Color measurement in XYZ and L*a*b*, Distance measurement between colors, Camera characteristic adjustment, Photography environment calibration, Color checker calibration

**Features:** macOS Compatibility

**In-app purchases:** none


### SIONYX

[App page](https://appshunter.io/ios/app/sionyx/id1642888573)

Stream video and control your SIONYX Nightwave and OPSIN devices. This app allows for seamless command and upgrade functions for your compatible night vision equipment.

**Highlights:** Video streaming, Command and control functions, Device upgrades, Nightwave device support, OPSIN device support

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is C free?

C costs $2.99, with no in-app purchases.

### Is SIONYX free?

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

### Which has better reviews, C or SIONYX?

SIONYX is rated higher. C averages 1.0 out of 5 from 1 ratings, while SIONYX averages 2.7 from 15 ratings.

### Do C or SIONYX have ads?

Neither C nor SIONYX shows ads.

### Which is updated more often, C or SIONYX?

C ships an update every 14 months, and SIONYX every 5 months. Most recently, C was updated on November 1, 2026 and SIONYX on October 6, 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.*