# Ruby Compiler vs Doomsday Trainer

The clearest difference is update cadence: Doomsday Trainer at every 5 days against Ruby Compiler's every 2 months. Ruby Compiler's advantage is iOS requirement (12.0 vs 15.0). On price, ads, in-app purchases and device support there is nothing between them.

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

Ruby Compiler ships an update every 2 months, Doomsday Trainer every 5 days. The most recent releases landed on October 1, 2026 and September 30, 2026 respectively.

## The numbers

| Metric | Ruby Compiler | Doomsday Trainer |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[4.0 (2 ratings)](https://appshunter.io/ios/app/doomsday-trainer/id6760719687/reviews)** |
| Number of ratings | — | **2** |
| Positive reviews | — | 0.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 2 months | **Every 5 days** |
| Monetization | — | Free |
| Size | 28 MB | 15 MB |
| Requires iOS | **12.0** | 15.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [OnePercent](https://appshunter.io/developer/1536020418) | [Maarten Claessen](https://appshunter.io/developer/1885901059) |

## What reviewers say

### Ruby Compiler

[App page](https://appshunter.io/ios/app/ruby-compiler-rub-rb-code/id1546362321)

**Features:** macOS Compatibility

**In-app purchases:** none


### Doomsday Trainer

[App page](https://appshunter.io/ios/app/doomsday-trainer/id6760719687)

Master the Doomsday Algorithm to instantly calculate the day of the week for any historical date. Engage in timed challenges, compete against others, and practice various calculation methods to improve your speed and accuracy.

**Highlights:** Doomsday Algorithm calculation, Timed streak challenges, 1-on-1 live battles, Multiple training methods, Targeted component drills, Step-by-step tutorial

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

**In-app purchases:** none


## Frequently asked questions

### Is Ruby Compiler free?

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

### Is Doomsday Trainer free?

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

### Do Ruby Compiler or Doomsday Trainer have ads?

Neither Ruby Compiler nor Doomsday Trainer shows ads.

### Which is updated more often, Ruby Compiler or Doomsday Trainer?

Ruby Compiler ships an update every 2 months, and Doomsday Trainer every 5 days. Most recently, Ruby Compiler was updated on October 1, 2026 and Doomsday Trainer on September 30, 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.*