# OCSI App vs First Light

The clearest difference is device support: OCSI App at 3 against First Light's 1. OCSI App also leads on iOS requirement (13.0 vs 17.0). On price, update cadence, ads and in-app purchases there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

OCSI App ships an update every 5 weeks, First Light every 3 weeks. The most recent releases landed on October 3, 2026 and October 15, 2026 respectively.

## The numbers

| Metric | OCSI App | First Light |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[5.0 (3 ratings)](https://appshunter.io/ios/app/first-light-cosmic-viewer/id6780022564/reviews)** |
| Number of ratings | — | **3** |
| Positive reviews | — | 100.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 5 weeks | **Every 3 weeks** |
| Monetization | — | Free |
| Size | 28 MB | 75 MB |
| Requires iOS | **13.0** | 17.0 |
| Devices | **iPhone, iPad, iPod** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [Okinawa Christian School International](https://appshunter.io/developer/1752812481) | [Thomas Sola](https://appshunter.io/developer/6780022566) |

## What reviewers say

### OCSI App

[App page](https://appshunter.io/ios/app/ocsi-app/id6504547732)

**Features:** macOS Compatibility

**In-app purchases:** none


### First Light

[App page](https://appshunter.io/ios/app/first-light-cosmic-viewer/id6780022564)

Explore the universe's earliest light with real cosmic microwave background data. Pan across the oldest light in the universe, switch between satellites, and observe shifts in frequency bands. This educational app brings real science and cosmic history to your mobile device.

**Highlights:** Explore cosmic microwave background data, Immersive sky exploration via phone movement, Switch between COBE, WMAP, and Planck satellites, Adjust frequency bands to see universe shifts, Utilizes real scientific data

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

**In-app purchases:** none


## Frequently asked questions

### Is OCSI App free?

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

### Is First Light free?

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

### Do OCSI App or First Light have ads?

Neither OCSI App nor First Light shows ads.

### Which is updated more often, OCSI App or First Light?

OCSI App ships an update every 5 weeks, and First Light every 3 weeks. Most recently, OCSI App was updated on October 3, 2026 and First Light on October 15, 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.*