# dob vs Grass Fire

The clearest difference is price: Grass Fire at Free against dob's $2.99. Grass Fire also leads on in-app purchases (none vs 1) and device support (3 vs 1). dob's advantage is update cadence (every 3 months vs every 15 months). On rating, ads and iOS requirement there is nothing between them.

Grass Fire is free to download; dob costs $2.99 up front. dob sells 1 one-off in-app purchase. Grass Fire asks for nothing beyond the download.

On the App Store both sit at effectively the same score — 1.0 for dob against 1.0 for Grass Fire. Both are backed by a comparable volume of ratings — 1 and 3 respectively.

dob ships an update every 3 months, Grass Fire every 15 months. The most recent releases landed on June 11, 2026 and September 17, 2026 respectively.

## The numbers

| Metric | dob | Grass Fire |
| --- | --- | --- |
| Price | $2.99 | **Free** |
| Rating | [1.0 (1 ratings)](https://appshunter.io/ios/app/dob-visual-perception/id981954512/reviews) | [1.0 (3 ratings)](https://appshunter.io/ios/app/grass-fire/id1440445499/reviews) |
| Number of ratings | 1 | **3** |
| Positive reviews | 0.0% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | **Every 3 months** | Every 15 months |
| Monetization | Paid | **Free** |
| Size | 78 MB | 66 MB |
| Requires iOS | 12.0 | 12.0 |
| Devices | iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Rene Fehr-Biscioni](https://appshunter.io/developer/969998405) | [arludo Pty Ltd](https://appshunter.io/developer/1023251086) |

## What reviewers say

### dob

[App page](https://appshunter.io/ios/app/dob-visual-perception/id981954512)

This app offers exercises to train essential visual skills like attention, coordination, and memory. It's designed for learners of all ages, including children and individuals undergoing rehabilitation, and can be customized to individual needs.

**Highlights:** Visual Attention training, Ocular motility exercises, Hand and Eye Coordination, Motion Perception, Contrast Sensitivity, Face and facial expression recognition, Color Recognition and differentiation, Figure-Ground Perception

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| All exercises | $11.99 | one-time |


### Grass Fire

[App page](https://appshunter.io/ios/app/grass-fire/id1440445499)

This educational app explores how the human brain interprets visual shapes. It's designed to help users understand the cognitive processes behind shape recognition and perception.

**Highlights:** Understanding shape interpretation, Cognitive process exploration, Visual perception testing, Educational content

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is dob free?

dob costs $2.99, and also offers in-app purchases.

### Is Grass Fire free?

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

### Which has better reviews, dob or Grass Fire?

dob and Grass Fire are both rated 1.0 out of 5 on the App Store, from 1 and 3 ratings respectively.

### Do dob or Grass Fire have ads?

Neither dob nor Grass Fire shows ads.

### Which is updated more often, dob or Grass Fire?

dob ships an update every 3 months, and Grass Fire every 15 months. Most recently, dob was updated on June 11, 2026 and Grass Fire on September 17, 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.*