# GreenBook vs SUB

The clearest difference is update cadence: SUB at fortnightly against GreenBook's every 3 months. GreenBook's advantage is iOS requirement (13 vs 18.0). 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.

GreenBook ships an update every 3 months, SUB fortnightly. The most recent releases landed on September 23, 2026 and October 1, 2026 respectively.

## The numbers

| Metric | GreenBook | SUB |
| --- | --- | --- |
| Price | Free | Free |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 3 months | **Fortnightly** |
| Monetization | Free | — |
| Size | 26 MB | 35 MB |
| Requires iOS | **13** | 18.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, Apple Watch |
| Age rating | 4+ | 12+ |
| Developer | [Tanner Mackenzie](https://appshunter.io/developer/1782692965) | [Marmak Industries Ltd](https://appshunter.io/developer/1603074782) |

## What reviewers say

### GreenBook

[App page](https://appshunter.io/ios/app/greenbook/id6738869708)

Access Ontario's Occupational Health and Safety Act and Regulations. This tool allows for easy searching, bookmarking, and highlighting of key passages to aid in workplace compliance. A downloadable safety board posting is also available.

**Highlights:** Access Ontario's Health and Safety Act, Searchable Regulations, Bookmark key passages, Highlight text, Global search across documents, Downloadable safety board posting

**Features:** macOS Compatibility

**In-app purchases:** none


### SUB

[App page](https://appshunter.io/ios/app/sub-zero/id6752495110)

**Features:** macOS Compatibility, Apple Watch app, Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is GreenBook free?

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

### Is SUB free?

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

### Do GreenBook or SUB have ads?

Neither GreenBook nor SUB shows ads.

### Which is updated more often, GreenBook or SUB?

GreenBook ships an update every 3 months, and SUB fortnightly. Most recently, GreenBook was updated on September 23, 2026 and SUB on October 1, 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.*