# SyncML PRO 4 vs SiYuan

The clearest difference is price: SiYuan at Free against SyncML PRO 4's $11.99. SiYuan also leads on update cadence (weekly vs every 17 months) and ratings volume (29 vs 1). SyncML PRO 4's advantage is rating (5.0 vs 4.0) and in-app purchases (none vs 2). On ads and device support there is nothing between them.

SiYuan is free to download; SyncML PRO 4 costs $11.99 up front. SiYuan sells 2 one-off in-app purchases. SyncML PRO 4 asks for nothing beyond the download.

SyncML PRO 4 holds the better App Store score, 5.0 against 4.0. That said, the two scores are not equally well evidenced: SiYuan has 29 ratings behind it against 1, so its average is the more settled of the two.

SyncML PRO 4 ships an update every 17 months, SiYuan weekly. The most recent releases landed on October 5, 2026 and October 15, 2026 respectively.

## The numbers

| Metric | SyncML PRO 4 | SiYuan |
| --- | --- | --- |
| Price | $11.99 | **Free** |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/syncml-pro-4/id1165983946/reviews)** | [4.0 (29 ratings)](https://appshunter.io/ios/app/siyuan/id1583226508/reviews) |
| Number of ratings | 1 | **29** |
| Positive reviews | — | 70.0% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 17 months | **Weekly** |
| Monetization | Paid | **Free with in-app purchases** |
| Size | 4 MB | 419 MB |
| Requires iOS | **10.0** | 17.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 17+ |
| Developer | [Lukas Zeller](https://appshunter.io/developer/299521020) | [Yunnan Liandi Technology Co., Ltd.](https://appshunter.io/developer/1583226510) |

## What reviewers say

### SyncML PRO 4

[App page](https://appshunter.io/ios/app/syncml-pro-4/id1165983946)

This app facilitates synchronization of contacts and calendars using the SyncML standard. It is designed for users who require this specific legacy technology, often in organizational settings, and need to connect to a SyncML-compliant server. It offers calendar views and enhanced contact group management.

**Highlights:** SyncML contacts and calendar synchronization, Connects to SyncML compliant servers, Acts as a local SyncML server, Calendar month, day, week, and list views, Contact group assignment feature

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

**In-app purchases:** none


### SiYuan

[App page](https://appshunter.io/ios/app/siyuan/id1583226508)

A privacy-focused personal knowledge management system that allows offline use and encrypted data synchronization. It combines blocks, outlines, and bidirectional links to help users organize and refine their thoughts.

**Highlights:** Privacy-first design, Offline data storage, End-to-end encrypted sync, Block-based organization, Outline structuring, Bidirectional linking

**Features:** Vision Pro support

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| PRO Features | $79.99 | one-time |
| Subscription | $188.99 | one-time |


## Frequently asked questions

### Is SyncML PRO 4 free?

SyncML PRO 4 costs $11.99, with no in-app purchases.

### Is SiYuan free?

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

### Which has better reviews, SyncML PRO 4 or SiYuan?

SyncML PRO 4 is rated higher. SyncML PRO 4 averages 5.0 out of 5 from 1 ratings, while SiYuan averages 4.0 from 29 ratings.

### Do SyncML PRO 4 or SiYuan have ads?

Neither SyncML PRO 4 nor SiYuan shows ads.

### Which is updated more often, SyncML PRO 4 or SiYuan?

SyncML PRO 4 ships an update every 17 months, and SiYuan weekly. Most recently, SyncML PRO 4 was updated on October 5, 2026 and SiYuan on October 15, 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.*