# US History Encyclopedia vs J. J. Keller® ERG App

The clearest difference is price: J. J. Keller® ERG App at Free against US History Encyclopedia's $0.99. J. J. Keller® ERG App also leads on update cadence (every 6 months vs every 47 months). US History Encyclopedia's advantage is iOS requirement (11.0 vs 16.2). On rating, ratings volume, ads and in-app purchases there is nothing between them.

J. J. Keller® ERG App is free to download; US History Encyclopedia costs $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.

On the App Store both sit at effectively the same score — 5.0 for US History Encyclopedia against 5.0 for J. J. Keller® ERG App. Both are backed by a comparable volume of ratings — 1 and 2 respectively.

US History Encyclopedia ships an update every 47 months, J. J. Keller® ERG App every 6 months. The most recent releases landed on October 24, 2026 and October 20, 2026 respectively.

## The numbers

| Metric | US History Encyclopedia | J. J. Keller® ERG App |
| --- | --- | --- |
| Price | $0.99 | **Free** |
| Rating | [5.0 (1 ratings)](https://appshunter.io/ios/app/us-history-encyclopedia/id1135262002/reviews) | [5.0 (2 ratings)](https://appshunter.io/ios/app/j-j-keller-erg-app/id6761837921/reviews) |
| Number of ratings | 1 | **2** |
| Positive reviews | 50.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 47 months | **Every 6 months** |
| Monetization | Paid | **Free** |
| Size | 121 MB | 129 MB |
| Requires iOS | **11.0** | 16.2 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 12+ |
| Developer | [Trang Hoai](https://appshunter.io/developer/1124304908) | [J. J. Keller & Associates, Inc.](https://appshunter.io/developer/684247627) |

## What reviewers say

### US History Encyclopedia

[App page](https://appshunter.io/ios/app/us-history-encyclopedia/id1135262002)

Access a comprehensive offline encyclopedia of United States history, covering government, science, culture, and more. Discover featured entries daily, create custom lists, and utilize voice search for easy navigation. Bookmark important topics for quick reference.

**Highlights:** Offline encyclopedia access, Over 17,581 entries, 5 featured entries daily, Custom list creation, Voice search functionality, Bookmark entries

**Features:** macOS Compatibility

**In-app purchases:** none


### J. J. Keller® ERG App

[App page](https://appshunter.io/ios/app/j-j-keller-erg-app/id6761837921)

This app offers quick access to emergency response guidance for hazardous materials incidents. It allows users to search, browse, and bookmark critical information from the Emergency Response Guidebook, supporting first responders and transportation professionals in critical situations.

**Highlights:** Fast access to ERG, Search by UN number or material name, Indexed and color-coded sections, Save bookmarks, Visual identification tools, Offline functionality, Light and dark mode

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

**In-app purchases:** none


## Frequently asked questions

### Is US History Encyclopedia free?

US History Encyclopedia costs $0.99, with no in-app purchases.

### Is J. J. Keller® ERG App free?

J. J. Keller® ERG App is free to download, with no in-app purchases.

### Which has better reviews, US History Encyclopedia or J. J. Keller® ERG App?

US History Encyclopedia and J. J. Keller® ERG App are both rated 5.0 out of 5 on the App Store, from 1 and 2 ratings respectively.

### Do US History Encyclopedia or J. J. Keller® ERG App have ads?

Neither US History Encyclopedia nor J. J. Keller® ERG App shows ads.

### Which is updated more often, US History Encyclopedia or J. J. Keller® ERG App?

US History Encyclopedia ships an update every 47 months, and J. J. Keller® ERG App every 6 months. Most recently, US History Encyclopedia was updated on October 24, 2026 and J. J. Keller® ERG App on October 20, 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.*