# Co vs Addition Algorithms

The clearest difference is price: Co at Free against Addition Algorithms's $0.99. Co also leads on update cadence (every 4 months vs every 18 months) and iOS requirement (10.0 vs 12.0). On ads, in-app purchases and device support there is nothing between them.

Co is free to download; Addition Algorithms costs $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Co ships an update every 4 months, Addition Algorithms every 18 months. The most recent releases landed on June 5, 2026 and September 15, 2026 respectively.

## The numbers

| Metric | Co | Addition Algorithms |
| --- | --- | --- |
| Price | **Free** | $0.99 |
| Rating | **[2.6 (17 ratings)](https://appshunter.io/ios/app/cowriter-universal/id915105799/reviews)** | — |
| Number of ratings | **17** | — |
| Positive reviews | 8.3% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 4 months** | Every 18 months |
| Monetization | Free | — |
| Size | 45 MB | 23 MB |
| Requires iOS | **10.0** | 12.0 |
| Devices | **iPhone, iPad, iPod** | iPad, Mac |
| Age rating | 4+ | 4+ |
| Developer | [Don Johnston Incorporated](https://appshunter.io/developer/674099735) | [Ventura Educational Systems](https://appshunter.io/developer/371324172) |

## What reviewers say

### Co

[App page](https://appshunter.io/ios/app/cowriter-universal/id915105799)

This app provides advanced word prediction and spelling support for students. It offers grammar-smart suggestions and access to millions of topic-specific dictionaries to aid in writing. Built-in text-to-speech functionality helps users review their work.

**Highlights:** Grammar-smart word prediction, Millions of topic-specific dictionaries, Flexspell™ technology for spelling errors, Built-in text-to-speech, Personalized vocabulary and settings

**Features:** macOS Compatibility

**In-app purchases:** none


### Addition Algorithms

[App page](https://appshunter.io/ios/app/addition-algorithms/id1400428741)

**In-app purchases:** none


## Frequently asked questions

### Is Co free?

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

### Is Addition Algorithms free?

Addition Algorithms costs $0.99, with no in-app purchases.

### Do Co or Addition Algorithms have ads?

Neither Co nor Addition Algorithms shows ads.

### Which is updated more often, Co or Addition Algorithms?

Co ships an update every 4 months, and Addition Algorithms every 18 months. Most recently, Co was updated on June 5, 2026 and Addition Algorithms on September 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.*