# eDPPT vs Light Spectrometer Wavelength

The clearest difference is in-app purchases: eDPPT at none against Light Spectrometer Wavelength's 7. eDPPT also leads on iOS requirement (13.0 vs 15.0). Light Spectrometer Wavelength's advantage is update cadence (every 2 months vs every 39 months). On price, ads and device support there is nothing between them.

Both are free to download. Light Spectrometer Wavelength sells 4 in-app purchases, starting at $0.99 per month. eDPPT asks for nothing beyond the download.

eDPPT ships an update every 39 months, Light Spectrometer Wavelength every 2 months. The most recent releases landed on October 19, 2026 and October 24, 2026 respectively.

## The numbers

| Metric | eDPPT | Light Spectrometer Wavelength |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[4.2 (96 ratings)](https://appshunter.io/ios/app/light-spectrometer-wavelength/id6450930820/reviews)** |
| Number of ratings | — | **96** |
| Positive reviews | — | 72.7% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 39 months | **Every 2 months** |
| Monetization | — | Free with in-app purchases |
| Size | 8 MB | 43 MB |
| Requires iOS | **13.0** | 15.0 |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [David Dieffenderfer](https://appshunter.io/developer/1344558121) | [Contechity AB](https://appshunter.io/developer/1649290454) |

## What reviewers say

### eDPPT

[App page](https://appshunter.io/ios/app/edppt/id1596289970)

**Features:** macOS Compatibility

**In-app purchases:** none


### Light Spectrometer Wavelength

[App page](https://appshunter.io/ios/app/light-spectrometer-wavelength/id6450930820)

This application analyzes light to determine its dominant wavelength in nanometers, frequency in terahertz, and period length in femtoseconds. It provides real-time measurements and allows users to save their findings with notes. The app is designed for measuring colored light sources.

**Highlights:** Measures dominant wavelength (nm), Measures frequency (THz), Measures period length (fs), Real-time measurement, Save measurements with notes, Optional calibration

**Features:** Vision Pro support

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Full Access | $0.99 | per month |
| Full access | $0.99 | per month |
| Full access | $4.99 | per year |
| Full access | $6.99 | one-time |


## Frequently asked questions

### Is eDPPT free?

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

### Is Light Spectrometer Wavelength free?

Light Spectrometer Wavelength is free to download, with in-app purchases available.

### Do eDPPT or Light Spectrometer Wavelength have ads?

Neither eDPPT nor Light Spectrometer Wavelength shows ads.

### Which is updated more often, eDPPT or Light Spectrometer Wavelength?

eDPPT ships an update every 39 months, and Light Spectrometer Wavelength every 2 months. Most recently, eDPPT was updated on October 19, 2026 and Light Spectrometer Wavelength 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.*