# Serial vs Strobe tachometer (RPM meter)

The clearest difference is price: Strobe tachometer (RPM meter) at Free against Serial's $2.99. Serial's advantage is in-app purchases (none vs 2). On update cadence, ads, device support and iOS requirement there is nothing between them.

Strobe tachometer (RPM meter) is free to download; Serial costs $2.99 up front. Strobe tachometer (RPM meter) sells 2 one-off in-app purchases. Serial asks for nothing beyond the download.

Serial ships an update every 7 months, Strobe tachometer (RPM meter) every 4 months. The most recent releases landed on September 2, 2026 and October 21, 2026 respectively.

## The numbers

| Metric | Serial | Strobe tachometer (RPM meter) |
| --- | --- | --- |
| Price | $2.99 | **Free** |
| Rating | — | **[4.3 (83 ratings)](https://appshunter.io/ios/app/strobe-tachometer-rpm-meter/id831460940/reviews)** |
| Number of ratings | — | **83** |
| Positive reviews | — | 69.0% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 7 months | **Every 4 months** |
| Monetization | — | Free with in-app purchases |
| Size | 5 MB | 16 MB |
| Requires iOS | 15.6 | 15.6 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Ralph Cos](https://appshunter.io/developer/573505028) | [Dmitriy Kharutskiy](https://appshunter.io/developer/817385891) |

## What reviewers say

### Serial

[App page](https://appshunter.io/ios/app/serial-sum-trainer/id577884595)

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

**In-app purchases:** none


### Strobe tachometer (RPM meter)

[App page](https://appshunter.io/ios/app/strobe-tachometer-rpm-meter/id831460940)

Measure rotational speeds of objects using your phone's flashlight, laser, or magnetic sensor. Detect precise RPMs with adjustable flicker frequencies and a wide measurement range. Ideal for analyzing fan speeds, engine RPMs, and more.

**Highlights:** Strobe tachometer function, Laser tachometer mode, Magnetic tachometer mode, Adjustable flicker frequency, RPM and Hz display, High precision measurement

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Full version of the stroboscopic tachometer | $2.99 | one-time |
| Laser Tachometer and Magnetic | $2.99 | one-time |


## Frequently asked questions

### Is Serial free?

Serial costs $2.99, with no in-app purchases.

### Is Strobe tachometer (RPM meter) free?

Strobe tachometer (RPM meter) is free to download, with in-app purchases available.

### Do Serial or Strobe tachometer (RPM meter) have ads?

Neither Serial nor Strobe tachometer (RPM meter) shows ads.

### Which is updated more often, Serial or Strobe tachometer (RPM meter)?

Serial ships an update every 7 months, and Strobe tachometer (RPM meter) every 4 months. Most recently, Serial was updated on September 2, 2026 and Strobe tachometer (RPM meter) on October 21, 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.*