# DiagonalOBDII vs BoostSpeed Pro

The clearest difference is in-app purchases: BoostSpeed Pro at none against DiagonalOBDII's 4. BoostSpeed Pro also leads on iOS requirement (12.0 vs 18.1). DiagonalOBDII's advantage is update cadence (every 2 weeks vs every 2 months). On price, ads and device support there is nothing between them.

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

DiagonalOBDII ships an update every 2 weeks, BoostSpeed Pro every 2 months. The most recent releases landed on October 22, 2026 and October 25, 2026 respectively.

## The numbers

| Metric | DiagonalOBDII | BoostSpeed Pro |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/diagonalobdii/id6743419784/reviews)** | — |
| Number of ratings | **1** | — |
| Positive reviews | 0.0% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | **Every 2 weeks** | Every 2 months |
| Monetization | Free with in-app purchases | — |
| Size | 21 MB | 36 MB |
| Requires iOS | 18.1 | **12.0** |
| Devices | iPhone | **iPhone, iPod** |
| Age rating | 4+ | 17+ |
| Developer | [Kyle Louderback](https://appshunter.io/developer/1400068218) | [ECU=SHOP](https://appshunter.io/developer/1389703440) |

## What reviewers say

### 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 |


### BoostSpeed Pro

[App page](https://appshunter.io/ios/app/boostspeed-pro/id6748590955)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is DiagonalOBDII free?

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

### Is BoostSpeed Pro free?

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

### Do DiagonalOBDII or BoostSpeed Pro have ads?

Neither DiagonalOBDII nor BoostSpeed Pro shows ads.

### Which is updated more often, DiagonalOBDII or BoostSpeed Pro?

DiagonalOBDII ships an update every 2 weeks, and BoostSpeed Pro every 2 months. Most recently, DiagonalOBDII was updated on October 22, 2026 and BoostSpeed Pro on October 25, 2026.

---

*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*