# Keystone Correction vs 書類フォルダ

Keystone Correction and 書類フォルダ both sit at 5.0 stars, but that hides the real split: 67% of Keystone Correction's written reviews are positive against 25% of 書類フォルダ's. Keystone Correction also leads on in-app purchases (none vs 1) and ratings volume (5 vs 1). 書類フォルダ's advantage is ads (none vs shown) and update cadence (every 2 days vs every 2 months). On price, rating and device support there is nothing between them.

Both are free to download. 書類フォルダ sells 1 one-off in-app purchase. Keystone Correction asks for nothing beyond the download.

On the App Store both sit at effectively the same score — 5.0 for Keystone Correction against 5.0 for 書類フォルダ. That said, the two scores are not equally well evidenced: Keystone Correction has 5 ratings behind it against 1, so its average is the more settled of the two. Written reviews are what separate them: 67% of Keystone Correction's written reviews are positive against 25% of 書類フォルダ's.

Keystone Correction ships an update every 2 months, 書類フォルダ every 2 days. The most recent releases landed on October 20, 2026 and October 14, 2026 respectively.

## The numbers

| Metric | Keystone Correction | 書類フォルダ |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [5.0 (5 ratings)](https://appshunter.io/ios/app/keystone-correction-comcam/id1504346555/reviews) | [5.0 (1 ratings)](https://appshunter.io/ios/app/id1549274564/reviews) |
| Number of ratings | **5** | 1 |
| Positive reviews | **66.7% of reviews** | 25.0% of reviews |
| In-app purchases | **No** | Yes |
| Ads | Yes | **No** |
| Update frequency | Every 2 months | **Every 2 days** |
| Monetization | Ad-supported | — |
| Size | 19 MB | 29 MB |
| Requires iOS | **11.0** | 14.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Masayoshi Shibata](https://appshunter.io/developer/1474388626) | [Takatoshi Fukino](https://appshunter.io/developer/789538982) |

## What reviewers say

### Keystone Correction

[App page](https://appshunter.io/ios/app/keystone-correction-comcam/id1504346555)

Easily scan and auto-correct documents directly on your device. This secure app keeps your images private by not uploading them online, making it ideal for sensitive business use. All functions are available for free, with no registration or complicated steps required.

**Highlights:** Automatic keystone correction, Secure offline processing, Easy document digitization, Free to use all functions, No user registration, Simple interface

**In-app purchases:** none


### 書類フォルダ

[App page](https://appshunter.io/ios/app/id1549274564)

**Features:** macOS Compatibility

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| 書類フォルダフルバージョン | $1.99 | one-time |


## Frequently asked questions

### Is Keystone Correction free?

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

### Is 書類フォルダ free?

書類フォルダ is free to download, with in-app purchases available.

### Which has better reviews, Keystone Correction or 書類フォルダ?

Keystone Correction and 書類フォルダ are both rated 5.0 out of 5 on the App Store, from 5 and 1 ratings respectively.

### Do Keystone Correction or 書類フォルダ have ads?

Keystone Correction shows ads; 書類フォルダ does not.

### Which is updated more often, Keystone Correction or 書類フォルダ?

Keystone Correction ships an update every 2 months, and 書類フォルダ every 2 days. Most recently, Keystone Correction was updated on October 20, 2026 and 書類フォルダ on October 14, 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.*