# Doppler Effect Calculator vs Contact Separator

Doppler Effect Calculator and Contact Separator both sit at 5.0 stars, but that hides the real split: 100% of Contact Separator's written reviews are positive against 0% of Doppler Effect Calculator's. Contact Separator also leads on price (Free vs $2.99) and update cadence (weekly vs every 26 months). Doppler Effect Calculator's advantage is in-app purchases (none vs 2). On rating, ratings volume, ads and device support there is nothing between them.

Contact Separator is free to download; Doppler Effect Calculator costs $2.99 up front. Contact Separator sells 2 in-app purchases, starting at $0.99 per month. Doppler Effect Calculator asks for nothing beyond the download.

On the App Store both sit at effectively the same score — 5.0 for Doppler Effect Calculator against 5.0 for Contact Separator. Both are backed by a comparable volume of ratings — 1 and 1 respectively. Written reviews are what separate them: 0% of Doppler Effect Calculator's written reviews are positive against 100% of Contact Separator's.

Doppler Effect Calculator ships an update every 26 months, Contact Separator weekly. The most recent releases landed on October 8, 2026 and October 9, 2026 respectively.

## The numbers

| Metric | Doppler Effect Calculator | Contact Separator |
| --- | --- | --- |
| Price | $2.99 | **Free** |
| Rating | [5.0 (1 ratings)](https://appshunter.io/ios/app/doppler-effect-calculator/id1410084954/reviews) | [5.0 (1 ratings)](https://appshunter.io/ios/app/contact-separator/id6477601880/reviews) |
| Number of ratings | 1 | 1 |
| Positive reviews | 0.0% of reviews | **100.0% of reviews** |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 26 months | **Weekly** |
| Monetization | Paid | **Free with in-app purchases** |
| Size | 1 MB | 7 MB |
| Requires iOS | 17.6 | **17.0** |
| Devices | **iPhone, iPad** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [Nitrio](https://appshunter.io/developer/321121189) | [Lars Herres](https://appshunter.io/developer/1713803692) |

## What reviewers say

### Doppler Effect Calculator

[App page](https://appshunter.io/ios/app/doppler-effect-calculator/id1410084954)

This physics and math calculator helps determine the frequency of sound waves when the source or observer is in motion. It provides instant calculations with copyable results and includes reference formulas. The app supports various units and high precision, working seamlessly on iOS devices.

**Highlights:** Instant calculations, Copyable results, Reference formulas included, Supports 16 decimal places, Multiple unit support, Ad-free and private

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

**In-app purchases:** none


### Contact Separator

[App page](https://appshunter.io/ios/app/contact-separator/id6477601880)

Organize and secure your contacts by separating them from your device's default list. This app identifies incoming callers and provides information in your call history, even for private contacts. It supports vCard import for easy management.

**Highlights:** Separate contacts from standard list, Caller Identification, Call History Identification, vCard Import, Privacy protection for contacts

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Monthly Abo | $0.99 | per month |
| Lifetime | $5.99 | one-time |


## Frequently asked questions

### Is Doppler Effect Calculator free?

Doppler Effect Calculator costs $2.99, with no in-app purchases.

### Is Contact Separator free?

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

### Which has better reviews, Doppler Effect Calculator or Contact Separator?

Doppler Effect Calculator and Contact Separator are both rated 5.0 out of 5 on the App Store, from 1 and 1 ratings respectively.

### Do Doppler Effect Calculator or Contact Separator have ads?

Neither Doppler Effect Calculator nor Contact Separator shows ads.

### Which is updated more often, Doppler Effect Calculator or Contact Separator?

Doppler Effect Calculator ships an update every 26 months, and Contact Separator weekly. Most recently, Doppler Effect Calculator was updated on October 8, 2026 and Contact Separator on October 9, 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.*