# ReactionFlash vs ACS Safety First

The clearest difference is update cadence: ReactionFlash at every 4 months against ACS Safety First's every 36 months. 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.

ReactionFlash ships an update every 4 months, ACS Safety First every 36 months. The most recent releases landed on October 23, 2026 and October 7, 2026 respectively.

## The numbers

| Metric | ReactionFlash | ACS Safety First |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.8 (42 ratings)](https://appshunter.io/ios/app/reactionflash/id432080813/reviews)** | — |
| Number of ratings | **42** | — |
| Positive reviews | 80.6% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 4 months** | Every 36 months |
| Monetization | Free | — |
| Size | 37 MB | 30 MB |
| Requires iOS | **14.0** | 15.6 |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Elsevier Limited](https://appshunter.io/developer/1437273934) | [American Chemical Society](https://appshunter.io/developer/355382933) |

## What reviewers say

### ReactionFlash

[App page](https://appshunter.io/ios/app/reactionflash/id432080813)

This app serves as a comprehensive flashcard-style learning tool for named chemical reactions. It provides detailed information on reaction mechanisms and examples from scientific literature, with a quiz mode to test user knowledge.

**Highlights:** Learn named chemical reactions, Understand reaction mechanisms, View literature examples, Quiz mode for knowledge testing, Flashcard interface

**Features:** macOS Compatibility

**In-app purchases:** none


### ACS Safety First

[App page](https://appshunter.io/ios/app/acs-safety-first/id6469359948)

**In-app purchases:** none


## Frequently asked questions

### Is ReactionFlash free?

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

### Is ACS Safety First free?

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

### Do ReactionFlash or ACS Safety First have ads?

Neither ReactionFlash nor ACS Safety First shows ads.

### Which is updated more often, ReactionFlash or ACS Safety First?

ReactionFlash ships an update every 4 months, and ACS Safety First every 36 months. Most recently, ReactionFlash was updated on October 23, 2026 and ACS Safety First on October 7, 2026.

---

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