# Engine RPM vs QuickScanPDF+

The clearest difference is review sentiment: QuickScanPDF+ at 100% against Engine RPM's 48%. QuickScanPDF+ also leads on price (Free vs $8.99) and rating (5.0 vs 4.0). Engine RPM's advantage is in-app purchases (none vs 2) and ads (none vs shown). On device support there is nothing between them.

QuickScanPDF+ is free to download; Engine RPM costs $8.99 up front. QuickScanPDF+ sells 2 in-app purchases, starting at $2.99 per month. Engine RPM asks for nothing beyond the download.

QuickScanPDF+ holds the better App Store score, 5.0 against 4.0. That said, the two scores are not equally well evidenced: Engine RPM has 35 ratings behind it against 1, so its average is the more settled of the two. Written reviews point the same way: 48% of Engine RPM's written reviews are positive against 100% of QuickScanPDF+'s.

Engine RPM ships an update every 16 months, QuickScanPDF+ weekly. Both last shipped on October 24, 2026.

## The numbers

| Metric | Engine RPM | QuickScanPDF+ |
| --- | --- | --- |
| Price | $8.99 | **Free** |
| Rating | [4.0 (35 ratings)](https://appshunter.io/ios/app/engine-rpm/id340401811/reviews) | **[5.0 (1 ratings)](https://appshunter.io/ios/app/quickscanpdf-plus/id6759846883/reviews)** |
| Number of ratings | **35** | 1 |
| Positive reviews | 47.7% of reviews | **100.0% of reviews** |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | Every 16 months | **Weekly** |
| Monetization | **Free** | Free with in-app purchases |
| Size | 3 MB | 19 MB |
| Requires iOS | **13.0** | 17.0 |
| Devices | iPhone, iPod | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Real-Time Specialties](https://appshunter.io/developer/335568332) | [Hatching Point LLC](https://appshunter.io/developer/1860158157) |

## What reviewers say

### Engine RPM

[App page](https://appshunter.io/ios/app/engine-rpm/id340401811)

Analyze engine sound to calculate RPM using advanced signal processing. Ideal for engine setup and diagnostics, it supports various engine types and provides real-time feedback for accurate readings.

**Highlights:** Acoustic RPM measurement, Engine sound analysis, Supports 2-stroke/4-stroke engines, Configurable cylinder count, Real-time autocorrelation graph, Adjustable update periods, Low-pass filtering

**Features:** Vision Pro support

**In-app purchases:** none

**What reviewers like**

- 💰 Saves money vs. dedicated tachometer
- 🛠️ Useful for engine tuning/diagnostics
- ✅ Works well with correct settings
- 🏎️ Accurate for steady RPMs
- 💡 Ingenious app concept

**What reviewers complain about**

- 📉 Inaccurate or unreliable readings
- ❓ Difficult to configure/use
- 💸 Waste of money (for many)
- 😵 Confusing interface/settings
- ⚡ Not good for rapidly changing RPMs

**Reported bugs**

- Does not register live RPM readings
- Displays incorrect or random numbers
- App opens then closes immediately
- Blank display or flashes incorrect data intermittently
- Cannot get consistent readings

**Requested features**

- Save configuration settings
- Option to display cycle/cylinder count on home screen
- Improved response time for transient surges
- Simplified or automated setup process
- Auto-scaling graphical display for easier harmonic matching


### QuickScanPDF+

[App page](https://appshunter.io/ios/app/quickscanpdf-plus/id6759846883)

Effortlessly convert paper documents, notes, and receipts into high-quality PDFs directly from your smartphone. Enhance scanned pages with various cleaning tools and export them for easy sharing or saving.

**Highlights:** Automatic edge detection and perspective correction, Add multiple pages to a single document, Manual boundary adjustments, Auto Clean, Brighten, Sharpen, Remove Background presets, Adjustable PDF quality and optimization, Share via iOS share sheet, On-device document management

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Monthly Premium | $2.99 | per month |
| Yearly Premium | $19.99 | per year |


## Frequently asked questions

### Is Engine RPM free?

Engine RPM costs $8.99, with no in-app purchases.

### Is QuickScanPDF+ free?

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

### Which has better reviews, Engine RPM or QuickScanPDF+?

QuickScanPDF+ is rated higher. Engine RPM averages 4.0 out of 5 from 35 ratings, while QuickScanPDF+ averages 5.0 from 1 ratings.

### Do Engine RPM or QuickScanPDF+ have ads?

QuickScanPDF+ shows ads; Engine RPM does not.

### Which is updated more often, Engine RPM or QuickScanPDF+?

Engine RPM ships an update every 16 months, and QuickScanPDF+ weekly. Most recently, Engine RPM was updated on October 24, 2026 and QuickScanPDF+ on October 24, 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.*