# HydroLog vs Sync Period

The clearest difference is in-app purchases: Sync Period at none against HydroLog's 7. HydroLog's advantage is update cadence (every 8 days vs every 3 months). On price, ads, device support and iOS requirement there is nothing between them.

Both are free to download. HydroLog sells 7 in-app purchases, starting at $0.99 per month. Sync Period asks for nothing beyond the download.

HydroLog ships an update every 8 days, Sync Period every 3 months. Both last shipped on October 31, 2026.

## The numbers

| Metric | HydroLog | Sync Period |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[5.0 (2 ratings)](https://appshunter.io/ios/app/sync-period/id6761670998/reviews)** |
| Number of ratings | — | **2** |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | **Every 8 days** | Every 3 months |
| Monetization | — | Free |
| Size | 6 MB | 6 MB |
| Requires iOS | 18.6 | **18.0** |
| Devices | **iPhone, Apple Watch** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [Andre Moura](https://appshunter.io/developer/1864639204) | [Start in June LLC](https://appshunter.io/developer/1831523078) |

## What reviewers say

### HydroLog

[App page](https://appshunter.io/ios/app/hydrolog-water-tracker/id6757146528)

**Features:** Apple Watch app

**In-app purchases (7)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Monthly | $0.99 | per month |
| HydroLog Premium 1 Month | $1.99 | per month |
| Annual | $1.99 | per month |
| Annual | $7.99 | per year |
| HydroLog Premium 1 Year | $12.99 | per year |
| Monthly | $12.99 | per month |
| Premium | $17.99 | one-time |


### Sync Period

[App page](https://appshunter.io/ios/app/sync-period/id6761670998)

This health app offers a simple and intuitive way to monitor your menstrual cycles. It allows you to log periods, emotions, symptoms, and energy levels, providing insights and reminders for your next cycle. Personalized notes and a monthly calendar view help you stay informed about your reproductive health.

**Highlights:** Period tracking, Symptom logging, Emotion tracking, Energy level logging, Cycle insights, Period reminders, Notes and calendar view

**In-app purchases:** none


## Frequently asked questions

### Is HydroLog free?

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

### Is Sync Period free?

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

### Do HydroLog or Sync Period have ads?

Neither HydroLog nor Sync Period shows ads.

### Which is updated more often, HydroLog or Sync Period?

HydroLog ships an update every 8 days, and Sync Period every 3 months. Most recently, HydroLog was updated on October 31, 2026 and Sync Period on October 31, 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.*