# KM1 vs Sync

The clearest difference is in-app purchases: Sync at none against KM1's 10. Sync also leads on update cadence (every 3 weeks vs every 4 months). KM1's advantage is iOS requirement (11.0 vs 15.1). On price, rating, ratings volume and ads there is nothing between them.

Both are free to download. KM1 sells 10 one-off in-app purchases. Sync asks for nothing beyond the download.

On the App Store both sit at effectively the same score — 5.0 for KM1 against 5.0 for Sync. Both are backed by a comparable volume of ratings — 2 and 1 respectively.

KM1 ships an update every 4 months, Sync every 3 weeks. The most recent releases landed on September 25, 2026 and October 3, 2026 respectively.

## The numbers

| Metric | KM1 | Sync |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [5.0 (2 ratings)](https://appshunter.io/ios/app/km1/id1465942659/reviews) | [5.0 (1 ratings)](https://appshunter.io/ios/app/sync-private-period-tracker/id6743987631/reviews) |
| Number of ratings | **2** | 1 |
| Positive reviews | — | 100.0% of reviews |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 4 months | **Every 3 weeks** |
| Monetization | Free | Free |
| Size | 18 MB | 41 MB |
| Requires iOS | **11.0** | 15.1 |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 4+ | 12+ |
| Developer | [Level48 GmbH](https://appshunter.io/developer/1465942658) | [Wei Jian Wong](https://appshunter.io/developer/1805425419) |

## What reviewers say

### KM1

[App page](https://appshunter.io/ios/app/km1/id1465942659)

This app tracks your running activities and allows you to participate in virtual events. It calculates altitude adjustments for fair competition and lets you challenge friends or join public races. Represent your region in international events.

**Highlights:** Activity tracking (distance, pace, calories), Virtual running competitions, Friend challenges, Altitude adjustment for fair races, Live audio race updates, Regional/international event participation

**Features:** macOS Compatibility

**In-app purchases (10)**

| Purchase | Price | Billing |
| --- | --- | --- |
| KM1 Competition Package 15 | $14.99 | one-time |
| KM1 Competition Package 18 | $17.99 | one-time |
| KM1 Competition Package 20 | $19.99 | one-time |
| KM1 Competition Package 25 | $24.99 | one-time |
| KM1 Competition Package 27 | $26.99 | one-time |
| KM1 Competition Package 30 | $29.99 | one-time |
| KM1 Competition Package 45 | $44.99 | one-time |
| KM1 Competition Package 50 | $49.99 | one-time |
| KM1 Competition Package 58 | $89.99 | one-time |
| KM1 Competition Package 60 | $99.99 | one-time |


### Sync

[App page](https://appshunter.io/ios/app/sync-private-period-tracker/id6743987631)

A privacy-focused period tracker that stores all your data locally on your device. It offers a simple and ad-free experience for managing your menstrual cycle.

**Highlights:** Privacy-focused design, Local data storage, Ad-free experience, Simple interface, Cycle tracking

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

**In-app purchases:** none


## Frequently asked questions

### Is KM1 free?

KM1 is free to download, with in-app purchases available.

### Is Sync free?

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

### Which has better reviews, KM1 or Sync?

KM1 and Sync are both rated 5.0 out of 5 on the App Store, from 2 and 1 ratings respectively.

### Do KM1 or Sync have ads?

Neither KM1 nor Sync shows ads.

### Which is updated more often, KM1 or Sync?

KM1 ships an update every 4 months, and Sync every 3 weeks. Most recently, KM1 was updated on September 25, 2026 and Sync on October 3, 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.*