# Co vs BDI

The clearest difference is rating: Co at 2.6 against BDI's 2.3. Co also leads on device support (3 vs 1) and iOS requirement (10.0 vs 13.0). BDI's advantage is update cadence (every 2 months vs every 4 months). On price, ratings volume, ads and in-app purchases there is nothing between them.

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

Co holds the better App Store score, 2.6 against 2.3. Both are backed by a comparable volume of ratings — 17 and 6 respectively.

Co ships an update every 4 months, BDI every 2 months. The most recent releases landed on November 1, 2026 and November 3, 2026 respectively.

## The numbers

| Metric | Co | BDI |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[2.6 (17 ratings)](https://appshunter.io/ios/app/cowriter-universal/id915105799/reviews)** | [2.3 (6 ratings)](https://appshunter.io/ios/app/bdi-3-mobile-data-solution/id1532433975/reviews) |
| Number of ratings | **17** | 6 |
| Positive reviews | 8.3% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 4 months | **Every 2 months** |
| Monetization | Free | Free |
| Size | 45 MB | 208 MB |
| Requires iOS | **10.0** | 13.0 |
| Devices | **iPhone, iPad, iPod** | iPad |
| Age rating | 4+ | 4+ |
| Developer | [Don Johnston Incorporated](https://appshunter.io/developer/674099735) | [RiversideInsights](https://appshunter.io/developer/1483738140) |

## 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


### BDI

[App page](https://appshunter.io/ios/app/bdi-3-mobile-data-solution/id1532433975)

This application assists in administering clinical assessments for child development. It offers guided digital support for scoring, timers, and reporting, functioning both online and offline. Users can manage student data and sync assessments for web-based access.

**Highlights:** Online and offline assessment administration, Guided digital scoring assistance, Basal and ceiling indicators, Built-in timers, Modular reporting options, Student data management

**Features:** Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is Co free?

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

### Is BDI free?

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

### Which has better reviews, Co or BDI?

Co is rated higher. Co averages 2.6 out of 5 from 17 ratings, while BDI averages 2.3 from 6 ratings.

### Do Co or BDI have ads?

Neither Co nor BDI shows ads.

### Which is updated more often, Co or BDI?

Co ships an update every 4 months, and BDI every 2 months. Most recently, Co was updated on November 1, 2026 and BDI on November 3, 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.*