# Giotto ScanTool vs DiagonalOBDII

The clearest difference is rating: DiagonalOBDII at 5.0 against Giotto ScanTool's 3.3. DiagonalOBDII also leads on update cadence (every 2 weeks vs every 3 months). Giotto ScanTool's advantage is in-app purchases (none vs 4) and review sentiment (31% vs 0%). On price and ads there is nothing between them.

Both are free to download. DiagonalOBDII sells 4 in-app purchases, starting at $12.99 per month. Giotto ScanTool asks for nothing beyond the download.

DiagonalOBDII holds the better App Store score, 5.0 against 3.3. That said, the two scores are not equally well evidenced: Giotto ScanTool has 44 ratings behind it against 1, so its average is the more settled of the two. Written reviews complicate that: 31% of Giotto ScanTool's written reviews are positive against 0% of DiagonalOBDII's, so the app with the better star average is not the one people write more warmly about.

Giotto ScanTool ships an update every 3 months, DiagonalOBDII every 2 weeks. The most recent releases landed on June 1, 2026 and August 22, 2026 respectively.

## The numbers

| Metric | Giotto ScanTool | DiagonalOBDII |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [3.3 (44 ratings)](https://appshunter.io/ios/app/giotto-scantool/id1294503417/reviews) | **[5.0 (1 ratings)](https://appshunter.io/ios/app/diagonalobdii/id6743419784/reviews)** |
| Number of ratings | **44** | 1 |
| Positive reviews | **30.8% of reviews** | 0.0% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 3 months | **Every 2 weeks** |
| Monetization | **Free** | Free with in-app purchases |
| Size | 912 MB | 21 MB |
| Requires iOS | **14.0** | 18.1 |
| Devices | **iPhone, iPad, iPod** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [AutoEnginuity](https://appshunter.io/developer/1294503416) | [Kyle Louderback](https://appshunter.io/developer/1400068218) |

## What reviewers say

### Giotto ScanTool

[App page](https://appshunter.io/ios/app/giotto-scantool/id1294503417)

This professional-grade automotive diagnostic tool provides extensive vehicle coverage and deep system access. It helps repair shops and fleet managers quickly service a wide range of vehicles with features like live data, bi-directional controls, and DTC reporting.

**Highlights:** Professional-grade enhanced coverage, Access to ABS, airbag, powertrain, and more, Live data and bi-directional controls, Adaptive resets and learns, DTC report output (XML/PDF), Graphing with pan and zoom, WIFI connectivity

**Features:** macOS Compatibility

**In-app purchases:** none


### DiagonalOBDII

[App page](https://appshunter.io/ios/app/diagonalobdii/id6743419784)

This app helps mechanics perform vehicle drive cycles more efficiently. It provides real-time monitoring of emissions monitors and diagnostic trouble codes (DTCs), offering clear guidance and instant explanations to ensure vehicles pass inspection quickly and accurately.

**Highlights:** Live drive cycle monitoring, Immediate diagnostic trouble code (DTC) identification, Real-time emissions monitor status, Precise drive cycle parameter guidance, Professional, easy-to-navigate dashboard, Instant code explanations

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Diagonal Premium Monthly | $12.99 | per month |
| Diagonal Premium Trial | $12.99 | per month |
| Shop Owner - Monthly | $17.99 | per month |
| Diagonal Premium Yearly | $99.99 | per year |


## Frequently asked questions

### Is Giotto ScanTool free?

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

### Is DiagonalOBDII free?

DiagonalOBDII is free to download, with in-app purchases available.

### Which has better reviews, Giotto ScanTool or DiagonalOBDII?

DiagonalOBDII is rated higher. Giotto ScanTool averages 3.3 out of 5 from 44 ratings, while DiagonalOBDII averages 5.0 from 1 ratings.

### Do Giotto ScanTool or DiagonalOBDII have ads?

Neither Giotto ScanTool nor DiagonalOBDII shows ads.

### Which is updated more often, Giotto ScanTool or DiagonalOBDII?

Giotto ScanTool ships an update every 3 months, and DiagonalOBDII every 2 weeks. Most recently, Giotto ScanTool was updated on June 1, 2026 and DiagonalOBDII on August 22, 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.*